Newsgroup sci.physics.fusion 26906

Directory

Arnie Frisch (arnief@wu.cse.tek.com) wrote:
: >Arnie Frisch (arnief@wu.cse.tek.com) wrote:
: >: >Does anyone know where I might look to buy some used lab equipment.  I'm
: >: >poor but I'm planning to perform some experiments in cool fusion. 
: >
: >: And you're about to become poorer.
: >: Whatever you want to do has been done.
: >
: >Kinda blows the whole point of buying your kid a chemistry set, ehy?
: I stand by the two lines above
They might or might not be accurate predictions, but they are hardly
logically defensible causal certainties.
: I challenge him to refute them by suggesting something that a poor,
: relatively inexperienced experimenter can do in his basement to advance
: the "science" of cold fusion - something that has not already been done.
A "challenge" even Nostradamas couldn't meet.
: Oh yes, I don't intend to hold my breath waiting for his response.
No wonder, he's dead.
--
 - John Logajan -- jlogajan@skypoint.com  --  612-699-9472 -
 - 4248 Hamline Ave; Arden Hills, Minnesota (MN) 55112 USA -
 -   WWW URL = http://www.skypoint.com/members/jlogajan    -

I am really interested in how Nuclear Fusion actually goes from being a
bunch of atoms into power that we can use.  It seems a little strange
that in fission, you smash apart a nucleus, and that gives off energy,
but it's a little hard to grasp the fact that when you do the opposite
thing, you can get even more power out of it.  If anyone can give me a
hand on this, I would really appreciate it!

Seth Clayton wrote:
> 
> I am really interested in how Nuclear Fusion actually goes from being a
> bunch of atoms into power that we can use.  It seems a little strange
> that in fission, you smash apart a nucleus, and that gives off energy,
> but it's a little hard to grasp the fact that when you do the opposite
> thing, you can get even more power out of it.  If anyone can give me a
> hand on this, I would really appreciate it!
The stable arrangements of protons and neutrons to form atoms are in the
middle of the periodic table.  It takes a lot of energy to split iron
into lots of smaller atoms.  Doing the reverse, say starting with
hydrogen or helium to make iron, gets the energy back again.
Now pushing up scale from iron also takes energy.  So to make uranium
you have to put energy in.  Split uranium up and you get energy out.
Little atoms apart store energy.
Big atoms store energy.
The middle atoms just sit there. :)

rvanspaa@netspace.net.au (Robin van Spaandonk) writes:
>
>Tell me Dick, just percentage of electricity produced in the US today,
>is as a result of matter going POOF?
 Dick must be out shoveling snow. 
 There are two possible answers.  Dick's definition of "matter" would 
 say almost zero (there is a little bit of positron emission around 
 that contributes to radioactive heating) since it is based on the 
 meaning associated with matter -vs- antimatter (baryon conservation). 
 All of energy produced, not just electricity generation, is a result 
 of mass changes appearing as energy, if you interpret "matter" as a 
 reference to the mass of a quantity of matter. 
-- 
 James A. Carr        |  "The half of knowledge is knowing
    http://www.scri.fsu.edu/~jac/       |  where to find knowledge" - Anon. 
 Supercomputer Computations Res. Inst.  |  Motto over the entrance to Dodd 
 Florida State, Tallahassee FL 32306    |  Hall, former library at FSCW. 

Seth Clayton wrote:
> 
> I am really interested in how Nuclear Fusion actually goes from being a
> bunch of atoms into power that we can use.  It seems a little strange
> that in fission, you smash apart a nucleus, and that gives off energy,
> but it's a little hard to grasp the fact that when you do the opposite
> thing, you can get even more power out of it.  If anyone can give me a
> hand on this, I would really appreciate it!
You need a good basic handbook on nuclear physics, and I always found 
Asimov could explain things much better than your average Joe.  Look for 
his "Guide to the Physical Sciences" and hope it is still in print. Let 
me try a very short version and see if this helps:
Whether splitting atoms (fissioning) or combining them (fusion), it is 
always true that the original components weigh more - have more total 
mass - than the end products.  This mass difference is where the energy 
comes from, the amount of the energy released being given by that famous 
equation:  E=mc2.  
If fusion releases more energy than fission, it is because the mass 
difference produced by fusion (per unit mass of the original components) 
is greater than for fission.
The snag is that some reactions which can release huge amounts of energy 
- like fusion - are also difficult to initiate.  It is still true that 
power from fusion is much harder to produce than from fission.  Very high 
temperatures and pressures are required for fusion to be productive.  
At least, this was the case before the whole Cold Fusion thing hit the 
press.  
I appreciate your question because it helps me keep focusing on the one 
crucial aspect of CF, which is that, unlike with conventional fusion, 
nobody has successfully and repeatably built any kind of useful power 
generator from CF.  No one has identified for certain if the process is 
real fusion - or even a nuclear phenomenon - again, as far as I can tell. 
If this not the case, then I wish someone would take the time to give us 
both a summary of just what has been found out for sure about CF, and 
whether it is going anywhere.  Thanks ..
DC

"Karim Alim"  writes:
>
>For you to blithely say, "Gee, I hope Miley thought of thus-and-so" is
>hardly a good answer to Miley's comment.  
 Nothing blithe about it.  (Why do we use the Old English adverb but 
 not the adjective?)  Although Miley identifies some of the problems 
 I chose to comment on, mainly as regards what theories they exclude, 
 he does not look at them critically as regards the null hypothesis. 
 That would require going back to the few real anomalies and checking 
 whether they were a result of misidentification of peaks.   
 Two things stand out to me: the absence of data tables for A < 28 
 (this may be an omission from the preprint and not the paper) that 
 address what goes on with the electrolyte, and the lack of comment 
 about the isotopic purity of the original material.  The latter is 
 either covered by patents (but cost would be an issue) or indicative 
 of the actual (never stated) uncertainties in those data. 
>Um, the "fact" that the Wright Brothers made no public claims about
>passenger service is well-documented?  I don't THINK so. 
  There is a great deal of history written about them and the 
  marketing of their product, the Wright Flyer.  
  I notice you chose not to comment on the two items of relevance 
  to this newsgroup's discussion, which I had assumed was your 
  central point.  Past claims made by P&F; and CETI are public record. 
>             ...                In any event, your "look it up" response is
>right up there with "the demonstration of this proof is left as an exercise
>to the reader."
  I would assume that a person making a claim or objecting to one 
  would be familiar with the history of the subject.  I would also 
  add that when the reader does not do any background work on a 
  problem, the reader learns a lot less than is possible by a more 
  involved effort.  In particular, if you have not followed this 
  subject for the past seven and a half years (my how time flies) 
  there could be some catching up to do. 
|   I do give credit to CETI for being more open about what they are 
|   doing than some of the other participants in cold fusion over the 
|   years.  What remains unclear is whether these new claims are any 
|   more reliable than the ones we saw made about heat. 
>Buy a RIFEX kit and let me know, okay?  
 Do you have a financial interest in the company?
 You know, if the folks here were not so burned out by claims made by 
 people associated with Jed, it might be possible to organize another 
 independent "s.p.f foundation" funded set of experiments like we did 
 with the last ones.   Maybe someone with more spare change is going 
 to try again with the CETI stuff like one of this forum did the last 
 time around, with heat, but the price has gone up a lot. 
|  >2) TALKING about KILOWATT OUTPUT in ONE EXPERIMENT is *NOT* the same thing
|  >as PROMISING FREE HOT WATER HEATERS FOR THE ENTIRE PLANET.
|  
|   It does correspond to a certain nuclear reaction rate if fusion is 
|   the source of that power output.  I leave it to you to calculate 
|   how many of these cells would be equivalent to your home hot water 
|   heater -- and what fraction of the input power of the device could 
|   be produced by direct thermo-electric conversion of the claimed output. 
>You're a prof, right?  "I leave it to you to calculate..."  Hello?  arms again>    Anyone home?  
  That was what I was asking.  Have you done anything more concrete 
  than speculate?  Do you know the personal risk when operating one 
  of these devices if it really does what is being claimed?  Do you 
  know that the CETI device should be able to power itself except 
  for the little detail that it needs a pump? 
  I do hope one of the purchasers does a careful set of experiments 
  and publishes them in the peer-reviewed literature. 
-- 
 James A. Carr        |  "The half of knowledge is knowing
    http://www.scri.fsu.edu/~jac/       |  where to find knowledge" - Anon. 
 Supercomputer Computations Res. Inst.  |  Motto over the entrance to Dodd 
 Florida State, Tallahassee FL 32306    |  Hall, former library at FSCW. 

Bradley K. Sherman (bks@netcom.com) wrote:
: When exactly did CETI devices change from excess heat
: thingamabobs to transmutation doohickeys?
Technically, never.   Fusion/fission are and always were considered 
transmutation processes -- cold, hot, or otherwise.
--
 - John Logajan -- jlogajan@skypoint.com  --  612-699-9472 -
 - 4248 Hamline Ave; Arden Hills, Minnesota (MN) 55112 USA -
 -   WWW URL = http://www.skypoint.com/members/jlogajan    -

Bradley K. Sherman (bks@netcom.com) wrote:
: I just skimmed the Vortex-L compedium and it doesn't
: look to me like any of the True Believers are voting
: with their wallets and buying one of the kits.
That's non-falsifiable since you don't define "true believer" and so
you could claim that anyone identified as buying one of the kits was
not among the set "true believer."
--
 - John Logajan -- jlogajan@skypoint.com  --  612-699-9472 -
 - 4248 Hamline Ave; Arden Hills, Minnesota (MN) 55112 USA -
 -   WWW URL = http://www.skypoint.com/members/jlogajan    -

Mike Asher  wrote in article
<01bbd8ac$a114f3a0$89d0d6cc@micron-p133>...
> M Simon  wrote:
> > 
> > 10% experimental error I might believe 3% even. 1% does not seem
> > credible.
> > 
> > I speak from experience as an electronic engineer.
> > 
> 
> If we can measure the speed of light to 18 signficant digit, I think we
can
> measure energy output to two digits.
The speed of light is a constant and is taken to be 299792458 meters/sec.
There is no need to measure it to 18 significant digits.
Larry
> 
> -
> Mike Asher
> masher@tusc.net
> 
> "In my own country, the UK, I like to point out that the average
> Englishman's garden occupies 1/10 of an acre.  By digging down 1 meter,
we
> can extract six kilograms of thorium, two kilograms of uranium, and 7,000
> kilograms of potassium, all of them radioactive.  In a sense, all of that
> is radioactive waste, not man-made, but the residue left over when God
> created the planet."
>    - Walter, Lord Marshall of Goring, head of CEGB.
> 
> 
> 

In article <579sn2$ok8@news.fsu.edu>, Jim Carr wrote :
>rvanspaa@netspace.net.au (Robin van Spaandonk) writes:
>>
>>Tell me Dick, just percentage of electricity produced in the US today,
>>is as a result of matter going POOF?
>
> Dick must be out shoveling snow. 
>
> There are two possible answers.  Dick's definition of "matter" would 
> say almost zero (there is a little bit of positron emission around 
> that contributes to radioactive heating) since it is based on the 
> meaning associated with matter -vs- antimatter (baryon conservation). 
>
> All of energy produced, not just electricity generation, is a result 
> of mass changes appearing as energy, if you interpret "matter" as a 
> reference to the mass of a quantity of matter. 
The latter is what I was referring to i.e. 100%.
However I had suspected that even Dick would have had to agree that nuclear
power met his definition.
I was just pointing out that even existing technology already proved that
his statement was "short sighted" to say the least.
But more to the point I wanted to point out that whether or not power is
produced (and how much) depends on precisely how certain materials are
manipulated. Nuclear weapons are the perfect example of this i.e. difficult
to get a good yield, if you don't do it exactly right.
Furthermore as has already been said by others:
Who would have believed a hundred years ago that a block of metal could
explode with such devastating power, all by itself? (i.e. without even
undergoing a chemical reaction! - preposterous! :)
Regards,
Robin van Spaandonk 
-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*
Check out: http://netspace.net.au/~rvanspaa for how CF depends on 
temperature.
"....,then he should stop, and he will catch up..."
-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*-*

In article <57a919$28b@stratus.skypoint.net>,
John Logajan  wrote:
>: I just skimmed the Vortex-L compedium and it doesn't
>: look to me like any of the True Believers are voting
>: with their wallets and buying one of the kits.
>
>That's non-falsifiable since you don't define "true believer" and so
>you could claim that anyone identified as buying one of the kits was
>not among the set "true believer."
Not exactly sure why this hit a nerve with you, John, but
I didn't see any names of long association with the debate
stating that they were buying kits, and that was my point.
If you can show that *anyone* who contributed to s.p.f during
the Droege experiments is now buying a CETI kit, I would
consider that a rebuttal of my assertion.
With regard to the transmutation versus excess heat issue:
I find claims that require a mass spectrograph to evaluate
in a different realm from those that require thermometers,
but I certainly concede your point that fusion implies
transmutation. 
Why, in your opinion, have the Cravens devices disappeared?
    --bks

rvanspaa@netspace.net.au (Robin van Spaandonk) writes:
>
>However I had suspected that even Dick would have had to agree that nuclear
>power met his definition.
  Then you should read the article he cited. 
  Nuclear power does not change the number of baryons present, 
  just their binding energy, just as chemical reactions do not 
  change the elements present.  The total lepton number does 
  not change either, although that is a messier bookkeeping problem. 
-- 
 James A. Carr        |  "The half of knowledge is knowing
    http://www.scri.fsu.edu/~jac/       |  where to find knowledge" - Anon. 
 Supercomputer Computations Res. Inst.  |  Motto over the entrance to Dodd 
 Florida State, Tallahassee FL 32306    |  Hall, former library at FSCW. 

Bradley K. Sherman (bks@netcom.com) wrote:
: >: I just skimmed the Vortex-L compedium and it doesn't
: >: look to me like any of the True Believers are voting
: >: with their wallets and buying one of the kits.
: >
: >That's non-falsifiable since you don't define "true believer" and so
: >you could claim that anyone identified as buying one of the kits was
: >not among the set "true believer."
: If you can show that *anyone* who contributed to s.p.f during
: the Droege experiments is now buying a CETI kit, I would
: consider that a rebuttal of my assertion.
That is a pretty expansive definition of "true believer." :-)
I know a couple of people who are trying to buy such kits, but whether
they are deemed "qualified" or not by the seller is yet another question.
If they get the kits, you will know shortly who they are, if not, I
guess it doesn't matter. :-)
: Why, in your opinion, have the Cravens devices disappeared?
Last I heard, there was an operating CETI device at the ANS meeting.
Do you mean "hidden in plain sight?" :-)
--
 - John Logajan -- jlogajan@skypoint.com  --  612-699-9472 -
 - 4248 Hamline Ave; Arden Hills, Minnesota (MN) 55112 USA -
 -   WWW URL = http://www.skypoint.com/members/jlogajan    -

Archive-name: fusion-faq/section0-intro/part1-overview
Last-modified: 26-Feb-1995
Posting-frequency: More-or-less-biweekly
Disclaimer:  While this section is still evolving, it should 
     be useful to many people, and I encourage you to distribute 
     it to anyone who might be interested (and willing to help!!!).
-----------------------------------------------------------------
### Answers to Frequently Asked Questions about Fusion Research
-----------------------------------------------------------------
# Written/Edited by:
     Robert F. Heeter
     
     Princeton Plasma Physics Laboratory
# Last Revised February 26, 1995
-----------------------------------------------------------------
*** A.  Welcome to the Conventional Fusion FAQ!  
-----------------------------------------------------------------
* 1) Contents
  This file is intended to indicate 
     (A) that the Conventional Fusion FAQ exists, 
     (B) what it discusses, 
     (C) how to find it on the Internet, and
     (D) the status of the Fusion FAQ project
* 2) What is the Conventional Fusion FAQ?
  The Conventional Fusion FAQ is a comprehensive, relatively
  nontechnical set of answers to many of the frequently asked
  questions about fusion science, fusion energy, and fusion
  research.  Additionally, there is a Glossary of Frequently
  Used Terms In Plasma Physics and Fusion Energy Research, which 
  explains much of the jargon of the field.  The Conventional 
  Fusion FAQ originated as an attempt to provide 
  answers to many of the typical, basic, or introductory questions 
  about fusion research, and to provide a listing of references and 
  other resources for those interested in learning more.  The
  Glossary section containing Frequently Used Terms (FUT) also
  seeks to facilitate communication regarding fusion by providing
  brief explanations of the language of the field.
* 3) Scope of the Conventional Fusion FAQ:
  Note that this FAQ discusses only the conventional forms of fusion
  (primarily magnetic confinement, but also inertial and 
  muon-catalyzed), and not new/unconventional forms ("cold fusion",
  sonoluminescence-induced fusion, or ball-lightning fusion).  I 
  have tried to make this FAQ as uncontroversial and comprehensive
  as possible, while still covering everything I felt was 
  important / standard fare on the sci.physics.fusion newsgroup.
* 4) How to Use the FAQ:
  This is a rather large FAQ, and to make it easier to find what
  you want, I have outlined each section (including which questions
  are answered) in Section 0, Part 2 (posted separately).  Hopefully it 
  will not be too hard to use.  Part (C) below describes how to find
  the other parts of the FAQ via FTP or the World-Wide Web.
* 5) Claims and Disclaimers:  
  This is an evolving document, not a completed work.  As such, 
  it may not be correct or up-to-date in all respects.  
  This document should not be distributed for profit, especially 
  without my permission.  Individual sections may have additional 
  restrictions.  In no case should my name, the revision date, 
  or this paragraph be removed.  
                                             - Robert F. Heeter
--------------------------------------------------------------------
*** B. Contents (Section Listing) of the Conventional Fusion FAQ
--------------------------------------------------------------------
*****************************************************************
                What This FAQ Discusses
*****************************************************************
(Each of these sections is posted periodically on sci.physics.fusion.
 Section 0.1 is posted biweekly, the other parts are posted quarterly.
 Each listed part is posted as a separate file.)
Section 0 - Introduction
     Part 1/3 - Title Page
                Table of Contents
                How to Find the FAQ
                Current Status of the FAQ project
     Part 2/3 - Detailed Outline with List of Questions
     Part 3/3 - Revision History
Section 1 - Fusion as a Physical Phenomenon
Section 2 - Fusion as an Energy Source
     Part 1/5 - Technical Characteristics
     Part 2/5 - Environmental Characteristics
     Part 3/5 - Safety Characteristics
     Part 4/5 - Economic Characteristics
     Part 5/5 - Fusion for Space-Based Power
Section 3 - Fusion as a Scientific Research Program
     Part 1/3 - Chronology of Events and Ideas
     Part 2/3 - Major Institutes and Policy Actors
     Part 3/3 - History of Achievements and Funding
Section 4 - Methods of Containment / Approaches to Fusion
     Part 1/2 - Toroidal Magnetic Confinement Approaches
     Part 2/2 - Other Approaches (ICF, muon-catalyzed, etc.)
Section 5 - Status of and Plans for Present Devices
Section 6 - Recent Results
Section 7 - Educational Opportunities
Section 8 - Internet Resources
Section 9 - Future Plans
Section 10 - Annotated Bibliography / Reading List
Section 11 - Citations and Acknowledgements
Glossary of Frequently Used Terms (FUT) in Plasma Physics & Fusion:
  Part 0/26 - Intro
  Part 1/26 - A
  Part 2/26 - B
  [ ... ]
  Part 26/26 - Z
---------------------------------------------------------------
*** C.  How to find the Conventional Fusion FAQ on the 'Net:
---------------------------------------------------------------
*****************************************************************
###  The FAQ about the FAQ:
###          How can I obtain a copy of a part of the Fusion FAQ?
*****************************************************************
* 0) Quick Methods (for Experienced Net Users)
   (A) World-Wide Web:  http://lyman.pppl.gov/~rfheeter/fusion-faq.html
   (B) FTP:  rtfm.mit.edu in /pub/usenet-by-group/sci.answers/fusion-faq
* 1) Obtaining the Fusion FAQ from Newsgroups
  Those of you reading this on news.answers, sci.answers, 
  sci.energy, sci.physics, or sci.environment will be able to 
  find the numerous sections of the full FAQ by reading 
  sci.physics.fusion periodically.  (Please note that not 
  all sections are completed yet.)  Because the FAQ is quite
  large, most sections are posted only every three months, to avoid
  unnecessary consumption of bandwidth.
  All sections of the FAQ which are ready for "official" 
  distribution are posted to sci.physics.fusion, sci.answers, 
  and news.answers, so you can get them from these groups by 
  waiting long enough. 
* 2) World-Wide-Web (Mosaic, Netscape, Lynx, etc.):
   Several Web versions now exist.
   The "official" one is currently at
     
   We hope to have a version on the actual PPPL Web server 
      () soon.
   There are other sites which have made "unofficial" Web versions 
   from the newsgroup postings.  I haven't hunted all of these down 
   yet, but I know a major one is at this address:
 
 Note that the "official" one will include a number of features
 which cannot be found on the "unofficial" ones created by
 automated software from the newsgroup postings.  In particular
 we hope to have links through the outline directly to questions,
 and between vocabulary words and their entries in the Glossary, 
 so that readers unfamiliar with the terminology can get help fast.
 (Special acknowledgements to John Wright at PPPL, who is handling
  much of the WWW development.)
* 3) FAQ Archives at FTP Sites (Anonymous FTP) - Intro
  All completed sections can also be obtained by anonymous FTP 
  from various FAQ archive sites, such as rtfm.mit.edu.  The
  address for this archive is:
    
  Please note that sections which are listed above as having
  multiple parts (such as the glossary, and section 2) are 
  stored in subdirectories, where each part has its own
  filename; e.g., /fusion-faq/glossary/part0-intro. 
  Please note also that there are other locations in the rtfm
  filespace where fusion FAQ files are stored, but the reference
  given above is the easiest to use.
  There are a large number of additional FAQ archive sites,
  many of which carry the fusion FAQ.  These are listed below.
* 4) Additional FAQ archives worldwide (partial list)
  There are other FAQ archive sites around the world
  which one can try if rtfm is busy; a list is appended
  at the bottom of this file.
* 5) Mail Server
   If you do not have direct access by WWW or FTP, the 
   rtfm.mit.edu site supports "ftp by mail": send a message 
   to mail-server@rtfm.mit.edu with the following 3 lines
   in it (cut-and-paste if you like): 
send usenet-by-group/sci.answers/fusion-faq/section0-intro/part1-overview
send usenet-by-group/sci.answers/fusion-faq/section0-intro/part2-outline
quit
   The mail server will send these two introductory 
   files to you.  You can then use the outline (part2)
   to determine which files you want.  You can receive
   any or all of the remaining files by sending another
   message with the same general format, if you substitute
   the file archive names you wish to receive, in place of the 
   part "fusion-faq/section0-intro/part1-overview", etc. used above.
* 6) Additional Note / Disclaimer: 
  Not all sections of the FAQ have been written
  yet, nor have they all been "officially" posted.
  Thus, you may not find what you're looking for right away.
  Sections which are still being drafted are only
  posted to sci.physics.fusion.  If there's a section 
  you can't find, send me email and I'll let you know 
  what's up with it. 
-----------------------------------------------------------------------
*** D. Status of the Conventional Fusion FAQ Project
-----------------------------------------------------------------------
* 1) Written FAQ Sections:
  Most sections have been at least drafted, but many sections are still
  being written.  Sections 2.3, 2.4, 2.5, 3.1, 3.2, 3.3, 4.1, 4.2, and 9
  remain to be completed.
  Those sections which have been written could use revising and improving.
  I am trying to obtain more information, especially on devices and 
  confinement approaches; I'm also looking for more information on 
  international fusion research, especially in Japan & Russia.
   *** I'd love any help you might be able to provide!! ***
* 2) Building a Web Version
  A "primitive" version (which has all the posted data, but isn't
  especially aesthetic) exists now.  Would like to add graphics and 
  cross-references to the Glossary, between FAQ sections, and 
  to other internet resources (like laboratory Web pages).  
* 3) Nuts & Bolts - 
  I'm looking for ways to enhance the distribution of the FAQ, and
  to get additional volunteer help for maintenance and updates.
  We are in the process of switching to automated posting via the 
  rtfm.mit.edu faq posting daemon.
* 4) Status of the Glossary:
 # Contains roughly 1000 entries, including acronyms, math terms, jargon, etc.
 # Just finished incorporating terms from the "Glossary of Fusion Energy"
   published in 1985 by the Dept. of Energy's Office of Scientific and
   Technical Information.
 # Also working to improve technical quality of entries (more formal.)
 # World Wide Web version exists, hope to cross-reference to FAQ.
 # Hope to have the Glossary "officially" added to PPPL Web pages.
 # Hope to distribute to students, policymakers, journalists, 
   scientists, i.e., to anyone who needs a quick reference to figure out 
   what we're really trying to say, or to decipher all the "alphabet 
   soup."  Scientists need to remember that not everyone knows those 
   "trivial" words we use every day.  The glossary and FAQ should be 
   useful in preparing for talks to lay audiences.  Students will 
   also find it useful to be able to look up unfamiliar technical jargon.
----------------------------------------------------------------------
*** E. Appendix: List of Additional FAQ Archive Sites Worldwide 
----------------------------------------------------------------------
(The following information was excerpted from the "Introduction to 
the *.answers newsgroups" posting on news.answers, from Sept. 9, 1994.)
Other news.answers/FAQ archives (which carry some or all of the FAQs
in the rtfm.mit.edu archive), sorted by country, are:
[ Note that the connection type is on the left.  I can't vouch
for the fusion FAQ being on all of these, but it should be
on some. - Bob Heeter ]
Belgium
-------
  gopher                cc1.kuleuven.ac.be port 70
  anonymous FTP         cc1.kuleuven.ac.be:/anonymous.202
  mail-server           listserv@cc1.kuleuven.ac.be  get avail faqs
Canada
------
  gopher                jupiter.sun.csd.unb.ca port 70
Finland
-------
  anonymous ftp         ftp.funet.fi/pub/doc/rtfm
France
------
  anonymous FTP         grasp1.insa-lyon.fr:/pub/faq
                        grasp1.insa-lyon.fr:/pub/faq-by-newsgroup
  gopher                gopher.insa-lyon.fr, port 70
  mail server           listserver@grasp1.univ-lyon1.fr
Germany
-------
  anonymous ftp         ftp.Germany.EU.net:/pub/newsarchive/news.answers
                        ftp.informatik.uni-muenchen.de:/pub/comp/usenet/news.answers
                        ftp.uni-paderborn.de:/doc/FAQ
                        ftp.saar.de:/pub/usenet/news.answers (local access only)
  gopher                gopher.Germany.EU.net, port 70.
                        gopher.uni-paderborn.de
  mail server           archive-server@Germany.EU.net
                        ftp-mailer@informatik.tu-muenchen.de
                        ftp-mail@uni-paderborn.de
  World Wide Web        http://www.Germany.EU.net:80/
  FSP                   ftp.Germany.EU.net, port 2001
  gopher index          gopher://gopher.Germany.EU.net:70/1.archive
                        gopher://gopher.uni-paderborn.de:70/0/Service/FTP
Korea
-----
  anonymous ftp         hwarang.postech.ac.kr:/pub/usenet/news.answers
Mexico
------
  anonymous ftp         mtecv2.mty.itesm.mx:/pub/usenet/news.answers
The Netherlands
---------------
  anonymous ftp         ftp.cs.ruu.nl:/pub/NEWS.ANSWERS
  gopher                gopher.win.tue.nl, port 70
  mail server           mail-server@cs.ruu.nl
Sweden
------
  anonymous ftp         ftp.sunet.se:/pub/usenet
Switzerland
-----------
  anonymous ftp         ftp.switch.ch:/info_service/usenet/periodic-postings
  anonymous UUCP        chx400:ftp/info_service/Usenet/periodic-postings
  mail server           archiver-server@nic.switch.ch
  telnet                nic.switch.ch, log in as "info"
Taiwan
------
  anonymous ftp         ftp.edu.tw:/USENET/FAQ
  mail server           ftpmail@ftp.edu.tw
United Kingdon
--------------
  anonymous ftp         src.doc.ic.ac.uk:/usenet/news-faqs/
  FSP                   src.doc.ic.ac.uk port 21
  gopher                src.doc.ic.ac.uk port 70.
  mail server           ftpmail@doc.ic.ac.uk
  telnet                src.doc.ic.ac.uk login as sources
  World Wide Web        http://src.doc.ic.ac.uk/usenet/news-faqs/
United States
-------------
  anonymous ftp         ftp.uu.net:/usenet
  World Wide Web        http://www.cis.ohio-state.edu:80/hypertext/faq/usenet/top.html

Archive-name: fusion-faq/section1-physics
Last-modified: 7-Aug-1994
Posting-frequency: More-or-less-monthly
Disclaimer:  While this section is still evolving, it should 
     be useful to many people, and I encourage you to distribute 
     it to anyone who might be interested (and willing to help!!!).
------------------------------------------------------------------
1. Fusion as a Physical Phenomenon
Last Revised August 7, 1994
Written by Robert F. Heeter, rfheeter@pppl.gov, unless
otherwise cited.
------------------------------------------------------------------
### Please let me know if anything here is unclear. ###
*** A.  What is fusion?
"Fusion" means many things when discussed on the newsgroup.  
Technically, "fusion" is short for "Nuclear Fusion," which describes
the class of reactions where two light nuclei fuse together, forming
a heavier nucleus.  This heavier nucleus is frequently unstable, and
sometimes splits (fissions) into two or more fragments.  "Fusion"
also refers to the type of energy produced, and a "fusion reactor"
describes an energy-producing facility which generates power via
fusion reactors.  Finally, "fusion" can also be used to refer to
the scientific program aimed at harnessing fusion for clean,
safe, and hopefully inexpensive energy production - a collaborative 
international program which has been carried on for the past 40-some 
years.  Each of these three uses - the technical, the energy
source, and the scientific research program - is discussed in
a separate section of this FAQ.  The technical aspects of
fusion are discussed below in this section.
*** B.  How does fusion release energy?
If you add up the masses of the particles which go into a fusion
reaction, and you add up the masses of the particles which come out,
there is frequently a difference.  According to Einstein's famous
law relating energy and mass, E=mc^2, the "mass difference" can
take the form of energy.  Fusion reactions involving nuclei lighter
than iron typically release energy, but fusion reactions involving
nuclei heavier than iron typically absorb energy.  The amount of
energy released depends on the specifics of the reaction; a table
of reactions is given further below to give an idea of the variety 
of fusion reactions.
Another way to look at this is to consider the "binding energy"
of the elements in question.  If the reactants are bound more
weakly than the products, then energy is released in the reaction.
"Binding energy" is the amount of energy you would have to put
into a system in order to pull its components apart; conversely,
in a system with high binding energy, a lot of energy is released
as the components are allowed to bond together.  Suppose you
had two balls connected by a long, thin rubber band, so that they
are not very tightly connected, and the rubber band can be broken
easily.  This is a system with low binding energy.  Now here's an
analogy to what happens in fusion:  imagine the long, thin 
rubber band suddenly being replaced by a short, thick one.  The
short thick one has to be stretched a lot in order to connect
to the two balls, but it wants to bind them more tightly, so it
pulls them together, and energy is released as they move towards
each other.  The low-binding energy, long rubber band system
has been replaced by a high-binding energy, short rubber band
system, and energy is released. 
*** C.  Where does fusion occur in nature?
The conditions needed to induce fusion reactions are extreme; 
so extreme that virtually all natural fusion occurs in stars, 
where gravity compresses the gas, until temperature and pressure 
forces balance the gravitational compression.  If there is enough 
material in the star, pressures and temperatures will grow
large enough as the star contracts that fusion will begin to occur 
(see below for the explanation why); the energy released will then 
sustain the star's temperature against losses from sunlight being 
radiated away.  The minimum mass needed to induce fusion is roughly 
one-tenth the sun's mass; this is why the sun is a star, but 
Jupiter is merely a (large) planet.  (Jupiter is about 1/1000th 
the sun's mass, so if it were roughly 100 times bigger, it
too would generate fusion and be a small, dim star.)
Stellar fusion reactions gradually convert hydrogen into helium.  
When a star runs out of hydrogen fuel, it either stops burning 
(becoming a dwarf star) or, if it is large enough (so that gravity 
compresses the helium strongly) it begins burning the helium into 
heavier elements.  Because fusion reactions cease to release 
energy once elements heavier than iron are involved, the larger 
stars also eventually run out of fuel, but this time they
collapse in a supernova.  Gravity, no longer opposed by the internal
pressure of fusion-heated gases, crushes the core of the star, 
forming things like white dwarfs, neutron stars, and black holes
(the bigger the star, the more extreme the result).  (For more 
details, try the sci.astro or sci.space.science newsgroups.)
*** D.  Why doesn't fusion occur anywhere else in nature?
Current scientific knowledge indicates that very little fusion
occurs anywhere else in nature.  The reason is because in order
to get two nuclei to fuse, you first have to get them close together.
(This is because the nuclear forces involved in fusion only act
at short range.)  However, because the two nuclei are both positively
charged, they repel each other electrically.  Nuclei will not fuse
unless either (a) they collide with enough energy to overcome the
electrical repulsion, or (b) they find a "sneaky" way to circumvent
their repulsion (see muon-catalyzed fusion in section 4).  The
energy required for fusion is so high that fusion only occurs in
appreciable amounts once the temperature gets over 10 million
degrees Kelvin, so (a) doesn't happen anywhere outside of stars.
Current knowledge suggests that the sort of processes that would
allow sneaky-fusion as in (b) are very rare, so there just isn't
much fusion in the everyday world.
*** E.  What are the basic fusion reactions?
While it is possible to take any two nuclei and get them to fuse,
it is easiest to get lighter nuclei to fuse, because they are
less highly charged, and therefore easier to squeeze together.
There are complicated quantum-mechanics rules which determine which
products you will get from a given reaction, and in what amounts
("branching ratios").  The probability that two nuclei fuse is
determined by the physics of the collsion, and a property called
the "cross section" (see glossary) which (roughly speaking) 
measures the likelihood of a fusion reaction.  (A simple analogy
for cross-section is to consider a blindfolded person throwing
a dart randomly towards a dartboard on a wall.  The likelihood 
that the dart hits the target depends on the *cross-sectional* 
area of the target facing the dart-thrower.  (Thanks to Rich
Schroeppel for this analogy.))
Below is an annotated list of many fusion reactions discussed 
on the newsgroup.  Note:  D = deuterium, T = tritium, p = proton,
n = neutron; these and the other elements involved are discussed 
in the glossary/FUT.  (FUT = list of Frequently Used Terms; section
10 of the FAQ.)  The numbers in parentheses are the energies
of the reaction products (in Millions of electron-Volts, see
glossary for details).  The percentages indicate the branching 
ratios.  More information on each of the elements is given below.
Table I:  Fusion Reactions Among Various Light Elements
D+D   -> T (1.01 MeV) + p (3.02 MeV) (50%)   
      -> He3 (0.82 MeV) + n (2.45 MeV) (50%)  <- most abundant fuel
      -> He4 + about 20 MeV of gamma rays (about 0.0001%; depends
                                           somewhat on temperature.)
      (most other low-probability branches are omitted below)
D+T   -> He4 (3.5 MeV) + n (14.1 MeV)  <-easiest to achieve
D+He3 -> He4 (3.6 MeV) + p (14.7 MeV)  <-easiest aneutronic reaction
                                     "aneutronic" is explained below.
T+T   -> He4 + 2n + 11.3 MeV
He3+T -> He4 + p + n + 12.1 MeV (51%)
      -> He4 (4.8) + D (9.5) (43%)
      -> He4 (0.5) + n (1.9) + p (11.9) (6%)  <- via He5 decay
p+Li6 -> He4 (1.7) + He3 (2.3)      <- another aneutronic reaction
p+Li7 -> 2 He4 + 17.3 MeV (20%)
      -> Be7 + n -1.6 MeV (80%)     <- endothermic, not good.
D+Li6 -> 2He4 + 22.4 MeV            <- also aneutronic, but you 
                                              get D-D reactions too.
p+B11 -> 3 He4 + 8.7 MeV <- harder to do, but more energy than p+Li6
n+Li6 -> He4 (2.1) + T (2.7)        <- this can convert n's to T's
n+Li7 -> He4 + T + n - some energy
From the list, you can see that some reactions release neutrons,
many release helium, and different reactions release different
amounts of energy (some even absorb energy, rather than releasing
it).  He-4 is a common product because the nucleus of He-4 is
especially stable, so lots of energy is released in creating it.
(A chemical analogy is the burning of gasoline, which is relatively 
unstable, to form water and carbon dioxide, which are more stable.  
The energy liberated in this combustion is what powers automobiles.)
The reasons for the stability of He4 involve more physics than I
want to go into here.
Some of the more important fusion reactions will be described below.  
These reactions are also described in Section 2 in the context of 
their usefulness for energy-producing fusion reactors.
*** F.  Could you tell me more about these different elements?
(Note: there's more information in the glossary too.)
Hydrogen    (p):  Ordinary hydrogen is everywhere, especially 
                    in water.
Deuterium   (D):  A heavy isotope of hydrogen (has a neutron in
                    addition to the proton).  Occurs naturally at 
                    1 part in 6000; i.e. for every 6000 ordinary 
                    hydrogen atoms in water, etc., there's one D.
Tritium     (T):  Tritium is another isotope of hydrogen, with two 
                    neutrons and a proton.  T is unstable  
                    (radioactive), and decays into Helium-3 with a
                    half-life of 12.3 years.  (Half the T decays
                    every 12.3 years.)  Because of its short 
                    half-life, tritium is almost never found in 
                    nature (natural T is mostly a consequence 
                    of cosmic-ray bombardment).  Supplies have been 
                    manufactured using fission reactors; world 
                    tritium reserves are estimated at a few 
                    kilograms, I believe.  Tritium can be made by 
                    exposing deuterium or lithium to neutrons.
Helium-3  (He3):  Rare light isotope of helium; two protons and a 
                    neutron.  Stable.  There's roughly 13 He-3 atoms 
                    per 10 million He-4 atoms.  He-3 is relatively 
                    abundant on the surface of the moon; this is 
                    believed to be due to particles streaming onto
                    the moon from the solar wind.  He3 can also be
                    made from decaying tritium.
Helium-4  (He4):  Common isotope of helium.  Trace component of the 
                    atmosphere (about 1 part per million?); also 
                    found as a component of "natural gas" in gas 
                    wells.
Lithium-6 (Li6):  Less common isotope of lithium.  3 protons, 3 
                    neutrons.  There are 8 Li-6 atoms for every 100 
                    Li-7 atoms.  Widely distributed in minerals and 
                    seawater.  Very active chemically.
Lithium-7 (Li7):  Common isotope of lithium.  3 protons, 4 neutrons.
                    See above info on abundance.
Boron      (B):   Common form is B-11 (80%).  B-10 20%.  
                    5 protons, 6 neutrons.  Also abundant on earth.
Note:  Separating isotopes of light elements by mass is not 
         particularly difficult.
*** G.  Why is the deuterium-tritium (D-T) reaction the easiest?
Basically speaking, the extra neutrons on the D and T nuclei make
them "larger" and less tightly bound, and the result is
that the cross-section for the D-T reaction is the largest.
Also, because they are only singly-charged hydrogen isotopes,
the electrical repulsion between them is relatively small.
So it is relatively easy to throw them at each other, and it 
is relatively easy to get them to collide and stick.  
Furthermore, the D-T reaction has a relatively high energy yield.
However, the D-T reaction has the disadvantage that it releases
an energetic neutron.  Neutrons can be difficult to handle,
because they will "stick" to other nuclei, causing them to
(frequently) become radioactive, or causing new reactions.
Neutron-management is therefore a big problem with the
D-T fuel cycle.  (While there is disagreement, most fusion
scientists will take the neutron problem and the D-T fuel,
because it is very difficult just to get D-T reactions to go.)
Another difficulty with the D-T reaction is that the tritium
is (weakly) radioactive, with a half-life of 12.3 years, so
that tritium does not occur naturally.  Getting the tritium
for the D-T reaction is therefore another problem.
Fortunately you can kill two birds with one stone, and solve
both the neutron problem and the tritium-supply problem at
the same time, by using the neutron generated in the D-T
fusion in a reaction like n + Li6 -> He4 + T + 4.8 MeV.
This absorbs the neutron, and generates another tritium,
so that you can have basically a D-Li6 fuel cycle, with
the T and n as intermediates.  Fusing D and T, and then
using the n to split the Li6, is easier than simply trying
to fuse the D and the Li6, but releases the same amount of
energy.  And unlike tritium, there is a lot of lithium
available, particularly dissolved in ocean water.
Unfortunately you can't get every single neutron to stick
to a lithium nucleus, because some neutrons stick to other
things in your reactor.  You can still generate as much
T as you use, by using "neutron multipliers" such as
Beryllium, or by getting reactions like
n + Li7 -> He4 + T + n (which propagates the neutron)
to occur.  The neutrons that are lost are still a problem,
because they can induce radioactivity in materials that
absorb them.  This topic is discussed more in Section 2.
*** H.  What is aneutronic fusion?
Some researchers feel the advantages of neutron-free fusion
reactions offset the added difficulties involved in getting
these reactions to occur, and have coined the term
"aneutronic fusion" to describe these reactions.
The best simple answer I've seen so far is this one:
(I've done some proofreading and modified the notation a bit.)
[ Clarifying notes by rfheeter are enclosed in brackets like this.]
>From: johncobb@emx.cc.utexas.edu (John W. Cobb)
>Risto Kaivola  wrote:
[[ Sorry I don't have the date or full reference for this anymore;
this article appeared in sci.physics.fusion a few months ago.]]
>>Basically, what is aneutronic fusion?  The term aneutronic
>>confuses me considerably.  Could you give me an example of
>>an aneutronic fusion reaction? How could energy be produced
>>using such a reaction?  Can there be a fusion reaction in which
>>a neutron is never emitted?
>
>Examples:
>
>D + He3 --> He4 + p + 18.1MeV 
>(deuteron + helium-3 --> helium-4 + proton + energy)
>
>p + Li6 --> He4 + He3 + 4.0MeV
>(proton + lithium-6 --> helium-4 + helium-3 + energy)
>
>D + Li6 --> 2 He4 + 22.4MeV
>(deuteron + lithium-6 --> 2 helium-4's + energy)
>
>p + B11 --> 3 He4 + 8.7Mev
>(proton + boron-11 --> 3 helium-4's + energy)
>
>All of these reactions produce no neutrons directly.
[[ Hence "aneutronic." ]] 
>There are also other reactions that have multiple branches possible,
>some of which do not produce neutrons and others that do 
>(e.g., D + D, p + Li7).
>
>The question is how do you get a "reactor" going and not get 
>any neutrons.  There are 2 hurdles here. The first is getting the
>fuel to smack together hard enough and often enough for fusion
>to occur.
>The easiest fusion reaction is D + T --> He4 + n (the D-T fuel 
>cycle). A magnetic reactor can initiate fusion in one of these 
>things at about a temperature of 10keV. 
[1 keV = 1000 eV = 11,000,000 (degrees) kelvin, more or less]. 
>The other reactions require much higher temperatures (for example 
>about 50KeV for the D+He3 reaction). This is a big factor of 5. 
>The second hurdle is neutron production via "trash" (secondary) 
>reactions.  That is, the main reaction may be neutron-free, 
>but there will be pollution reactions that may emit neutrons. 
[ The products of the main reaction, e.g. He3, can be trapped in
your reactor temporarily, and fuse with other ions in the system 
in messy ways. ]
>Even if this is only a few percent, it can lead to big neutron
>emission. For example, the D+He3 reaction will also have some D+D 
>reactions occuring. 
[ Because in your reactor you will have a lot of Ds and He3s, and
the Ds will collide with each other as well as with the He3s. ]
>At 50Kev temperatures, the reaction 
>cross-section for D+D reactions is about 1/2 of the D+He3 
>cross-section, so there will be some generation of neutrons from 
>the 50% branch reaction of D + D-->He3 + n.
>Also, the other 50% goes to T+p, The triton (T) will then undergo 
>a D-T reaction and release another neutron. 
[ Because the cross-section for D-T reactions is much higher.]
>If the reactor is optmized (run in a He3 rich mode) the number 
>of neutrons can be minimized. The neutron power can be as low 
>as about 5% of the total. However, in a 1000 megawatt reactor, 
>5% is 50 MW of neutron power. That is [still] a lot of neutron 
>irradiation. This lower neutron level helps in designing 
>structural elements to withstand neutron bombardment, but it 
>still has radiation consequences.
>
>On the other hand, it is my understanding that the p-B11 reaction 
>is completely neutron free, but of course it is much harder 
>to light.
*** I.  What sort of fusion reactor is the sun?
Fortunately for life on earth, the sun is an aneutronic fusion
reactor, and we are not continually bombarded by fusion neutrons.
Unfortunately, the aneutronic process which the sun uses is 
extremely slow and harder to do on earth than any of the reactions
mentioned above.  The sun long ago burned up the "easy" deuterium
fuel, and is now mostly ordinary hydrogen.  Now hydrogen has a
mass of one (it's a single proton) and helium has a mass of four
(two protons and two neutrons), so it's not hard to imagine sticking
four hydrogens together to make a helium.  There are two major
problems here:  the first is getting four hydrogens to collide 
simultaneously, and the second is converting two of the four protons
into neutrons.  
The sun evades the first problem, and solves the second, by using a 
catalyzed cycle:  rather than fuse 4 protons directly, it fuses a 
proton to an atom of carbon-12, creating nitrogen-13; the N-13 emits 
a neutrino and a positron (an antielectron, that is an electon with
positive instead of negative charge) and becomes carbon-13.  
(Effectively, the Carbon-12 converted the proton to a 
neutron + positron + neutrino, kept the neutron, and became C-13).  
The C-13 eventually fuses with another proton to become N-14.  
N-14 then fuses with a proton to become oxygen-15.  Oxygen-15 decays 
to N-15 (emitting another positron), and N-15 plus another proton 
yields carbon-12 plus a helium-4 nucleus, (aka an alpha particle).  
Thus 4 protons are tacked one by one onto heavier elements, two of 
the protons are converted to neutrons, and the result is production
of helium and two positrons.  (The positrons will undergo 
matter-antimatter annihilation with two electrons, and the result
of the whole process is formation of a helium, two neutrinos, and
a bunch of gamma rays.  The gamma rays get absorbed in the solar 
interior and heat it up, and eventually the energy from all this 
fusion gets emitted as sunlight from the surface of the sun.)
The whole process is known as the carbon cycle; it's catalyzed
because you start with carbon and still have carbon at the end.
The presence of the carbon merely makes it possible to convert
protons to helium.  The process is slow because it's difficult
to fuse protons with carbon and nitrogen, and the positron-emitting
nuclear decays are also slow processes, because they're moderated
by the weak nuclear force.
*** J.  Why is it so hard to create controlled man-made fusion 
reactions?
In order to get two nuclei to fuse, you basically have to get
them to collide energetically.  It turns out that colliding two
beams of particles yields mostly scattering collisions, and few
fusion reactions.  Similarly, blasting a stationary target with
a beam of energetic ions also yields too little fusion.  
The upshot is that one must find some way to confine hot, 
energetic particles so that they can collide many many times,
and finally collide in just the right way, so that fusion occurs.
The temperatures required are upwards of 100 million degrees 
(Kelvin - it would be about 200 million Fahrenheit!).  At these
temperatures, your fusion fuel will melt/evaporate any material
wall.  So the big difficulties in fusion are (a) getting 
the particles hot enough to fuse, and (b) confining them long
enough so that they do fuse.
*** K.  What is plasma physics, and how is it related to fusion?
Plasma physics is the area of physics which studies ionized 
gases and their properties.  In most conventional types of fusion 
(muon-catalyzed fusion being the major exception), one must heat 
the fusion fuel to extremely high temperatures.  At these 
temperatures, the fuel atoms collide so much and so hard that 
many electrons are knocked loose from their atoms.  The result 
is a soup of ionized atoms and free electrons: a plasma.
In order to achieve the conditions required for controlled 
fusion, an understanding of how plasmas behave (and particularly 
how to confine and heat them) is often essential.
*** L.  Just how hot and confined do these plasmas need to be?
(Or, what conditions are needed for controlled fusion?)
Basically, the hotter your plasma, the more fusion you will have,
because the more ions will be flying around fast enough to stick
together.  (Although actually you can go *too* fast, and the atoms
then start to whiz by too quickly, and don't stick together long 
enough to fuse properly.  This limit is not usually achieved in 
practice.)  The more dense your plasma is, the more ions there are
in a small space, and the more collisions you are likely to have.
Finally, the longer you can keep your plasma hot, the more likely
it is that something will fuse, so duration is important too.  More
importantly, the slower your plasma loses energy, the more likely
it is that it will be able to sustain its temperature from internal
fusion reactions, and "ignite."  The ratio of fusion energy
production to plasma energy loss is what really counts here.
Hotness is measured by temperature, and as explained above, the
D-T fuel cycle (the easiest) requires temperatures of about 10 keV,
or 100,000,000 degrees kelvin.  Density is typically measured in 
particles-per-cubic centimeter or particles-per-cubic meter.
The required density depends on the confinement duration.
The Lawson product, defined as (density)*(confinement time) is a 
key measure of plasma confinement, and determines what 
combinations of density and energy confinement will give you 
fusion at a given temperature.  It is important to note that 
what you must confine is the *energy* (thermal energy) stored 
in the plasma, and not necessarily the plasma particles.  
There's a lot of subtlety here; for instance, you want to 
confine your fuel ions as well as their energy, so that they
stick around and fuse, but you *don't* want to confine the 
"ash" from the reactions, because the ash needs to get out 
of the reactor...  But you'd like to get the *energy*
out of the ash to keep your fuel hot so it will fuse better!
(And it gets even more complicated than that!)
Regardless, it's true that for a special value of the Lawson 
product, the fusion power produced in your plasma will just 
balance the energy losses as energy in the plasma becomes 
unconfined, and *ignition* occurs.  That is, as long as 
the plasma fuel stays around, the plasma will keep itself 
hot enough to keep fusing.
A simple analogy here is to an ordinary fire.  The fire won't
burn unless the fuel is hot enough, and it won't keep burning
unless the heat released by burning the fuel is enough to keep
the fuel hot enough.  The flame continually loses heat, but 
usually this loss is slow enough that the fire sustains itself.
You can accelerate the heat loss, however, by pouring water
on the fire to cool it quickly; this puts the fire out.
In fusion, the plasma continually loses heat, much as a fire 
gives off heat, and if the plasma loses heat faster than heat
is produced by fusion, it won't stay hot enough to keep burning.
In fusion reactors today, the plasmas aren't quite confined well
enough to sustain burning on their own (ignition), so we get
them to burn by pumping in energy to keep them hot.  This is sort
of like getting wet wood to burn with a blowtorch (this last analogy 
is usually credited to Harold Furth of PPPL).
For the D-T fuel cycle, the Lawson ignition value for a temperature 
of about 200,000,000 Kelvin is roughly 5E20 seconds-particles/m^3.  
Current fusion reactors such as TFTR have achieved about 1/10th of
this - but 20 years ago they had only achieved 1/100,000th of this!
How can we improve the Lawson value of a plasma further, so we get 
even closer to fusion ignition?  The trick is to keep the heat in the 
plasma for as long as possible.  As an analogy to this problem, 
suppose we had a thermos of coffee which we want to keep hot.  We can 
keep the thermos hotter longer by (a) using a better type of 
insulation, so that the heat flows out more slowly, or (b) using 
thicker insulation, so the heat has farther to go to escape, and
therefore takes longer to get out.
Going back to the fusion reactor, the insulation can be improved by 
studying plasmas and improving their insulating properties by 
reducing heat transport through them.  And the other way to boost
the Lawson value is simply to make larger plasmas, so the energy
takes longer to flow out.  Scientists believe it's technically
feasible to build a power-producing fusion reactor with high
Lawson value *Right Now*, but it would have to be large, so large 
in fact that it would cost too much to be able to make electricity
economically.  So we're studying plasmas and trying to figure out
how to make them trap energy more efficiently.
*** M.  What are the basic approaches used to heat and confine 
the plasma?  (Or, what is magnetic confinement?  
Inertial confinement?)
There are three basic ways to confine a plasma.  The first is 
the method the sun uses:  gravity.  If you have a big enough
ball of plasma, it will stick together by gravity, and be
self-confining.
Unfortunately for fusion researchers, that doesn't work here on
earth.  The second method is that used in nuclear fusion bombs:
you implode a small pellet of fusion fuel.  If you do it quickly
enough, and compress it hard enough, the temperature will go way
up, and so will the density, and you can exceed the Lawson 
ignition value despite the fact that you are only confining your
pellet for nanoseconds.  Because the inertia of the imploding
pellet keeps it momentarily confined, this method is known as
inertial confinement.
The third method uses the fact that charged particles placed in
a magnetic field will gyrate in circles.  If you can arrange the
magnetic field carefully, the particles will be trapped by it.
If you can trap them well enough, the plasma energy will be
confined.  Then you can heat the plasma, and achieve fusion with
more modest particle densities.  This method is known as 
magnetic confinement.  Initial heating is achieved by a 
combination of microwaves, energetic/accelerated particle beams, 
and resistive heating from currents driven through the plasma.
(Once the Lawson ignition value is achieved, the plasma becomes
more-or-less self-heating.)  In magnetic confinement, the plasma 
density is typically about 1E20 particles per cubic meter, and with
a temperature of about 1E8 kelvin, we see that ignition could be
achieved with a confinement time of about 4 seconds.  (All these 
numbers in reality vary by factors of 2 or 3 from the rough values 
I've given.)  Currently, magnetic-confinement reactors are about 
a factor of ten short of the ignition value.  (TFTR has an
energy confinement time of 0.25 seconds during its best shots.)  
More information on these different approaches is given in the
sections that follow.

Archive-name: fusion-faq/section0-intro/part2-outline
Last-modified: 26-Feb-1995
Posting-frequency: More-or-less-quarterly
-------------------------------------------------------------------
### Outline and List of Questions in the Conventional Fusion FAQ
-------------------------------------------------------------------
# Written/Edited by Robert F. Heeter, rfheeter@pppl.gov.
# (Outline subject to change; this list current on February 26, 1995)
*** 1. Fusion as a Physical Phenomenon:
     [Archive-name: fusion-faq/section1-physics]
        A.  What is fusion?
        B.  How does fusion release energy?
        C.  Where does fusion occur in nature?
        D.  Why doesn't fusion occur anywhere else in nature?
        E.  What are the basic fusion reactions?
        F.  Could you tell me more about these different elements?
        G.  Why is the deuterium-tritium (D-T) reaction the easiest?
        H.  What is aneutronic fusion?
        I.  What sort of fusion reactor is the sun? 
        J.  Why is it so hard to create controlled man-made fusion reactions?
        K.  What is plasma physics, and how is it related to fusion?
        L.  Just how hot and confined do these plasmas need to be?
                        (Or, what conditions are needed for controlled fusion?)
        M.  What are the basic approaches used to heat and confine 
                        the plasma?  (Or, what is magnetic confinement?  
                        Inertial confinement?)  
*** 2. Fusion as a Future Energy Source:
 2.1 Technical Characteristics
     [Archive-name: fusion-faq/section2-energy/part1-tech]
        A.  What would a fusion energy plant look like?
        B.  What fuels can a fusion reactor burn?
        C.  What are the different methods for converting fusion energy
                to useful energy?
        D.  What would a D-T fusion reactor look like?
        E.  How do you get the plasma hot enough for fusion to occur?
        F.  What are the materials requirements for fusion?  
        G.  Are any of these materials scarce?
        H.  How large would a fusion reactor be?  Why?
 2.2 Environmental Characteristics
     [Archive-name: fusion-faq/section2-energy/part2-enviro]
        A.  What are fusion's major potential environmental advantages?
        B.  But isn't fusion nuclear?  What about radioactive waste?
        C.  What key technologies are needed to achieve these advantages?
        D.  What are the materials and fuel requirements for fusion?
        E.  What about renewable energy sources?  
               Why do we need fusion at all?  
 2.3 Safety Characteristics Economic Characteristics  
     (Under construction)
 2.4 Economic Characteristics  
     (Under construction)
 2.5 Fusion for Space Applications  
     (Under construction)
*** 3. Fusion as a Scientific Research Program
 3.1 Chronology of Events and Ideas
     (Under construction)
              When did fusion research begin?
              When was fusion research declassified?
       What is the current state of fusion research? 
                   Close / far from achieving practical benefits?
 3.2 Major Institutes and Policy Actors
     (Under construction)
       Who is doing fusion, and where?  (funds distribution?)
              What level of international cooperation is there?
 3.3 History of Achievements and Funding
        (Under construction)
           What is the history of fusion funding (US, FUSSR, EC, Japan)?
              What is the history of achievement of fusion parameters?
*** 4. Methods of Confinement / 
                Approaches to fusion:
 4.1 Toroidal Magnetic Confinement Approaches
     (Under construction)
        A. What is a tokamak / how does it work?
        B. What is a stellarator / " " " " ? 
        C.   "  " reversed-field pinch / " " " " ? 
        D. What is a Field-Reversed Configuration / how does it work?
        E.   "  "  " Plasmak / "   "    "   " ? 
        F. What is a Migma / how does it work?
 4.2 Alternative Confinement Methods / Approaches
     (Under construction)
        A. Gravitational Confinement    
        B. Inertial Confinement
        C. Mirror Confinemen
        D. Muon-catalyzed Fusion
        E. Electrostatic Confinement 
        F. What about the pinch methods?
        G. What are some other confinement approaches?
*** 5. Status of and plans for Present Devices:
     [Archive-name: fusion-faq/section5-devices]
        A.  Flagship Tokamaks
                1.  ITER: (International Thermonuclear Experimental Reactor)
                2.  JET: (Joint European Torus)  
                3.  JT-60: (Japan Tokamak (?)) 
                4.  TFTR:  (Tokamak Fusion Test Reactor)  
                5.  TPX: (Tokamak Physics Experiment)  
        B.  Medium to Large Tokamaks
                1.  Alcator C-Mod: 
                2.  ASDEX-U:  (Axially Symmetric Divertor EXperiment-Upgrade) 
                3.  DIII-D:  (Doublet III, D-shape)
                4.  FT: (Frascati Tokamak)
                5.  NSTX: (National Spherical Tokamak eXperiment)
                6.  PBX-M:  (Princeton Beta Experiment-Modified)
                7.  TCV: (Variable Configuration Tokamak - in French) 
                8.  TdeV:  (Tokamak de Varenne)
                9.  TEXTOR:  
                10. Tore Supra:  
        C.  Small Tokamaks
                1:  CDX-U (Current Drive eXperiment-Upgrade)
                2.  START:  (Small, Tight-Aspect-Ratio Tokamak)
                3.  TEXT-U: (Texas Experimental Tokamak-Upgrade?)
        D.  Stellarators
                1.  ATF  (Advanced Toroidal Facility)  
                2.  Wendelstein-7AS:  (Advanced Stellarator) 
                3.  Wendelstein-7X
        E.  Inertial Confinement
                1.  NIF:  (National Ignition Facility)
                2.  Nova:
                3.  Omega:
                4.  NIKE:
        F.  Alternative Methods
                1.  Electrostatic Confinement:
                2.  MFTF:  Mirror Fusion Test Facility:  
                3.  Muon-Catalyzed Fusion 
                4.  Plasmak: 
                5.  RFX:  (Reversed-Field eXperiment)
*** 6. Recent Results
     [Archive-name: fusion-faq/section6-results]
        A.  Recent Results on TFTR:
                 (a) What was done?
                 (b) Why does it matter?
        B.  Recent Results from JET
        C.  Recent Results from Inertial Confinement Fusion
        D.  Recent Results from Muon-Catalyzed Fusion
        E.  Recent major results from other experiments, and theoretical work
        F.  Recent Political News
        G.  Appendix on TFTR and JET results
*** 7. Educational Issues and Conferences:
     [Archive-name: fusion-faq/section7-education]
        A.  What opportunities are there for interested students?
        B.  I'm an undergraduate interested in becoming a "fusioneer."  
                What should I study?
        C.  What sorts of experiments are there for high-school students?  
                How can I get the equipment?  Has anyone else done this?
        D.  What about those summer programs you mentioned above?       
        E.  When/where are the major fusion conferences?
*** 8. Internet Resources:
     [Archive-name: fusion-faq/section8-internet]
        A. Newsgroups
        B. WAIS (Wide-Area-Information-Server)
        C. World-Wide Web
        D. Gopher
        E. Anonymous FTP Sites
        F. Listservers
        G. Electronic Bulletins
        H. Individuals Willing to Provide Additional Information
*** 9. Future Plans:
  (Under construction)
        (a) Plans for TPX?
        (b) Plans for ITER?
        (c) Prospects for funding? (US, EC, Japan, FUSSR)
        (d) What problems in designing a fusion powerplant?
                Rad waste, materials choices, device parameters ???
        (e) What are the key research problems/opportunities?
*** 10. Bibliography / Reading List
     [Archive-name: fusion-faq/section10-biblio]
        A. Recent articles in the popular literature.
        B. General References and Histories 
           (suitable for those with minimal background in physics or fusion).
        C. Fusion Research Review Articles & Texts
        D. Plasma Physics - General Texts 
         (focus is on the science of plasmas, rather than engineering reactors)
        E.  Plasma Physics - Device-Specific
                (applications of plasma physics to specific devices)
        F. Fusion Reactor Engineering References
        G. List of Relevant Scientific Journals
        H. Unclassified / Unsummarized works.  (Please help me move
                references out of this section and into sections 1-4 by
                contributing reviews of sources you know about!)
*** 11. Acknowledgements and Citations
     [Archive-name: fusion-faq/section11-acknowledgements]
(I've had a lot of help, so I needed a separate section to list everyone!)
*** Glossary of Frequently Used Terms in Plasma Physics
     and Fusion Energy Research (FUT)
Part 0/26: Introduction to the Glossary / FUT 
     [Archive-name: fusion-faq/glossary/part0-intro]
Parts 1/26, 2/26, ..., 26/26: 
    Glossary terms from A to Z (one file per letter)  
    [ Archive-names: fusion-faq/glossary/a
                     fusion-faq/glossary/b
                     ...
                     fusion-faq/glossary/z ]