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.