Newsgroups: sci.physics.fusion,sci.answers,news.answers
Subject: Conventional Fusion FAQ Section 6/11 (Recent Results)
From: rfheeter@pppl.gov
Approved: news-answers-request@MIT.EDU
Followup-To: sci.physics.fusion
Reply-To: rfheeter@pppl.gov
Summary: Fusion energy represents a promising alternative to 
         fossil fuels and nuclear fission for world energy 
         production. This FAQ answers Frequently Asked Questions
         (from the sci.physics.fusion newsgroup) about conventional 
         areas of fusion energy research. It also provides other 
         useful information about the subject. This FAQ does NOT 
         discuss unconventional forms of fusion (like Cold Fusion). 
Expires: 1 Dec 1994 0:00:00 GMT

Archive-name: fusion-faq/section6-results
Last-modified: 16-Oct-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!!!).

*****************************************************************
6. Recent Results in Fusion Research

Last Revised October 16, 1994
Written by Robert F. Heeter, rfheeter@pppl.gov, unless
otherwise cited.

( This section discusses major fusion results from the past
     few years. )

***  A.  Recent Results on TFTR: D-T Experiments

* (a) What was done?

The Tokamak Fusion Test Reactor (TFTR) here at Princeton 
switched from pure-deuterium fuel to a deuterium-tritium 
(D-T) fuel mixture in December 1993.  As discussed in 
Section 1, the D-T fuel is easier to fuse, but the neutrons 
produced in the reaction D + T -> 4He + n will slowly make 
the reactor radioactive, so this set of experiments will 
be the last for TFTR.  In these reactions, over 6 million 
watts (MW) of fusion power were produced for about a second.  
This is four times more power than any previous controlled 
fusion experiment.  The value of 6 MW should be compared to
the roughly 30 MW of input power used, which indicates that
fusion in TFTR remains short of breakeven.  (See glossary for
explanations of unfamiliar terminology.)

(There was an article on this in _Time_, Dec 20, 1993, p. 54, 
at least in the American edition; there are of course other 
articles out there too.  See Section 9, Part A (the bibliography
on recent literature) for more references.)

>>Update May 31 (mostly from TFTR News Updates by Rich Hawryluk):  
   Over 9 megawatts were generated in late May.
     This is 90 million times what could be generated in 1974
     when TFTR was proposed.
   Input power was up to 33.7 MW -> Q = 0.27.  
     This means we are making almost as much fusion power as
     is used to heat the plasma now.
   Two articles on the December experiments were published in
     the May 30 issue of Physical Review Letters.
			Recent TFTR shots have exhibited exceptionally high performance,
     with preliminary indications that energy confinement is 
     enhanced by 20-30 percent in D-T relative to D-D fuel.
   Plasma disruptions possibly caused by TAE mode activity have
     been observed.  Fusion performance is limited by the MHD
     activity, not by heating power or confinement.
   Central fusion power density has been increased from 1.25 MW m-3
     to 1.8 MW m-3.

>>Update August 7
   Work is ongoing to try to stabilize the power-limiting modes.
>>Update September 13
   Funding to continue D-T experiments throughout FY 1995 has
   been granted. (see below)

>>Update October 16
   Though TFTR has not literally achieved "breakeven" (fusion power
     output equals plasma heating power input), we are very close
     now, and in addition we have achieved plasma conditions very
     close to those needed in a real fusion powerplant.  The
     scientific results achieved suggest that D-T plasmas have
     better confinement than their D-D counterparts.  A number of
     crucial scientific issues have been resolved and the sense
     of the scientists here is that we can be fairly confident
     that we can build a fusion reactor which will generate 
     gigawatts of surplus energy.  The trick now is to find ways
     to do this an an environmental and cost-effective manner.


*	(b) Why does it matter?

The generation of multi-megawatt levels of fusion power is a major
achievement for the controlled fusion program.  Sustaining the
power output for a second is also significant, because most
known plasma instabilities occur much more quickly.  Also, use 
of tritium to achieve high power levels enables researchers to 
study plasmas under conditions closer to those of a working 
fusion reactor.  There are effects due to the heavier tritium 
ions, and due to the presence of highly energetic helium ions
produced in the fusion reaction.  In particular, scientists
were worried that the energetic He ions might trigger new plasma
instabilities.  (Plasmas are notorious for finding new ways to
misbehave whenever scientists manage to improve the operating 
conditions.)  Fortunately, no major instabilities were observed,
and in fact early reports are that plasma performance actually
improves in high-power D-T conditions.  These results enhance
the prospects for future experiments which will try to achieve
even higher power outputs in nearly steady-state conditions.
(See Section 8 for more information on future experiments.)


***  B.  Recent Results on JET

JET ran some experiments in 1991 using a 10% tritium mix, and 
produced 1.7 megawatts of fusion power.  Since then researchers
have been reconfiguring the machine.  (Anybody know if plasma
operation has begun?)
 
Appended below are comments adapted from a post I made on Feb 12, 
1994 (which in turn referenced a Dec 14, 1993 posting by 
Stephen Cooper at JET), which provide more background to the 
JET & TFTR results.  


***  C.  Recent Results in Inertial Confinement Fusion

(Anybody got any info?  I haven't had time to look yet.)


***  D.  Recent Results in Muon-Catalyzed Fusion
(Based on information provided by Steven Jones of BYU.)

Steven Jones posted on April 30:

>In article <1994Apr27.214422.17681@debug.cuc.ab.ca>,
>Lforbes@debug.cuc.ab.ca writes:
>
>>I have heard little lately (last year or so) about muon catalyzed 
>>fusion; have there been any noteable developments?
>
>Not lately.  Not much has happened since DoE decided to cut funding 
>in 1988, the year *before* cold fusion hit the fan, incidentally.
>Despite the funding cut, we were able to do some experiments at 
>LAMPF in 1989 and 1990, and we recently published a paper 
>on results:
>S.E. Jones, S.F. Taylor and A.N. Anderson, "Evaluation of 
>muon-alpha sticking from liquid, non-equilibrated d-t targets 
>with high tritium fractions," 
>Hyperfine Interactions 82 (1993) 303-311.
>
>Other groups (PSI, Russia) are plugging along, and we're trying to
>work out an international collaboration with them which looks 
>fairly good right now, though funding is tight.


***  E.  Recent major results from other experiments, and 
theoretical work?



(Anyone care to contribute anything major?)


***  F.  Recent Political News

* (a) U.S. Magnetic Fusion News:

Congress postponed construction of TPX for a year pending
(hopeful) passage of the fusion authorization bill.  Design 
funding for TPX has been continued.  TPX construction funding 
has been diverted to provide funds to extend D-T 
experimentation on TFTR.  The authorization legislation was
passed by both house and Senate, but the bills had conflicting
provisions and Congress did not complete passage of a final bill
this session.  The process will begin anew in the next legislative
session.

Meanwhile, Robert Hirsch has been hired by General Atomics.
Hirsch is the former head of the fusion program and was recently
working at the Electric Power Research Institute (EPRI).

* (b) U.S. Inertial Fusion News

(Are there any ICF gurus out there?)


* (c) ITER News:

Paul-Henri Rebut has been succeeded as head of ITER by
Robert Aymar.  Concerns over ITER management have 
been receiving press lately.


* (d) European News:

(What's going on in Europe these days?)


* (e) Other world fusion news:

(Japan?)


***  G.  Appendix on TFTR and JET results

*********************************************
TFTR results vs JET results from 1991:
(Written by Stephen R. Cooper at JET, with comments [like this] 
by R.F. Heeter.)

>From src@jet.uk Tue Dec 14 11:14:34 EST 1993
Newsgroups: sci.physics.fusion
Subject: Re: Laymen Q: Was Princeton's Fusion a 'breakthrough?'
Organization: Joint European Torus
References: <2ebdvg$44e@Mercury.mcs.com> <2ei3vk$o7o@mailer.fsu.edu>
Date: Tue, 14 Dec 1993 12:01:28 GMT

In <2ei3vk$o7o@mailer.fsu.edu> jac@ds8.scri.fsu.edu (Jim Carr)
writes:
>As I recall, the reports from JET in November 1991 indicated a Q of
>about 1/9 for the light load of T, with plans to increase the T 
>to 50% by 1996.  I think their extrapolation to 50% indicated 
>they would be very close to breakeven at that point, but do not
>recall the details. 

>Could some JET person fill us in?

[ Note by rfheeter: Q is the ratio of power produced in the
machine by fusion to power put into the machine to heat
the plasma. Q = 1 means fusion yield is equal to power
input.  Economical fusion will require Q significantly 
greater than 1.  See the glossary (Section 10) for more details.]

Results quoted from "The JET Preliminary Tritium Experiment", 
invited talk given to the 1992 International Conference on 
Plasma Physics by P-H Rebut, Innsbruck, Austria, 29th June-3rd 
July 1992).

"Two Deuterium plasmas were heated by high power deuterium 
neutral beams from fourteen sources and fuelled by two neutral 
beam sources injecting tritium. In the best of the two D-T 
discharges, the tritium concentration was about 11% of bulk plasma 
at peak performance, when the total neutron emmision rate was 
6.0E17 per second, with 1.7MW of fusion power. The fusion 
amplification factor Q(DT) was 0.15. With an optimum tritium 
concentration, this pulse would have produced a fusion power 
of ~ 5MW and nominal Q(DT) of 0.46. The same extrapolation for 
the best pure deuterium discharge of the PTE series gives about 
11MW and a nominal Q(DT) of 1.14.

[ Note by rfheeter:  neutral beams are made by accelerating
deuterium ions, and then neutralizing the ions so that they
can fly into the magnetic field of the tokamak without being
deflected.  As they enter the plasma, they are re-ionized
and their energy is subsequently shared with the other 
ions in the plasma.  Thus this is a method for simultaneously
heating and refueling the plasma. See glossary for more info...]

The total integrated total neutron yield was 7.2E17 with an 
accuracy of +/- 7% and the total fusion energy was about 2MJ. 
The tritium injections last just 2 seconds out of a 10 second, 
3MA flat top. The amount of tritium injected and the limited 
number of shots were deliberatly restricted for operational 
convenience."

[ Note by rfheeter:  2 MJ = 2 million joules = 1 million
watts for a duration of 2 seconds, or 2 million watts for
a duration of one second.  1 Joule = 1 watt * 1 second.
A "10 second, 3 MA flat top" refers to the relatively stable
flat peak of a current-vs-time graph, indicating that
the plasma current is stable at about 3 million amps
(3 MA) for 10 seconds.  "Operational convenience" should
probably be interpreted as "because we didn't want to
make our reactor too radioactive, and tritium handling
is a pain." - that's an editorial comment. ]

--> Personal remarks start 
[this Cooper writing now, and not quoting others.]

The above seems to indicate that if JET had gone into it's full 
D-T phase at this time and with this configuration, we certainly
should have got to 50% of breakeven. As to if we could have 
matched our best deuterium pulse, I guess we would have come 
close especially as the TFTR results show no pathological 
problems with a 50/50 D-T mix. But this is all hypothetical, 
we no longer have anything like the configuration we had in 
1991, we're just about to finish a major shutdown incorporating 
a pumped divertor to look at impurity control and ash removal. 
The old H mode shots that the 1991 experiment were based on 
are a thing of the past and we'll have to wait and see how she 
performs with the new configuration.

[ Note by rfheeter: a "divertor" is a magnetic or physical
way of channeling particles from the edge of the plasma
out of the way, and helps to improve confinement of the plasma
as well as remove impurities. "H mode" is a relatively
stable operational mode of the tokamak, as contrasted with
"L mode", which is less stable.  I believe H = High and
L = Low, referring to high and low confinement.]

[[ The rest of the article was about TFTR and not JET,
and I have omitted it to save some space. ]]

Stephen R Cooper                 Physics Operations Group
src@jet.uk               Operations Division, JET.
-	Disclaimer: Please note that the above is a personal view and 
should not be construed as an official comment from the JET project.