Tracking Fusion Progress and Performance Gains

[etudiant]

There are a number of fusion threads, but no ongoing coverage of progress in the space, which continues apace.
It would be useful to maintain a summary of the current efforts and the high water mark performances achieved.
Afaik, the rate of gain to date suggests that performance (measured by confinement time and temperature) improves by about a factor of 10 every decade. Researchers think another factor of 100 should enable workable fusion devices. The ITER schedule is somewhat off that pace, unsurprising as it was an example of UN style management until recently, but the Wendelstein 7 is reportedly working as expected and looks promising.
Hopefully some of the more expert forum participants would chime in and keep us up to date.

 

[the_wolfman]

Hopefully some of the more expert forum participants would chime in and keep us up to date

There is a huge disconnect between what I consider progress and what's consider news worthy progress. In my opinion in the last couple of years there has been a lot of progress in areas like disruption avoidance and mitigation, elm control and suppression, non-inductive current drive, etc. These are all areas of concern that we need to address for ITER and beyond. Often there are not simple metrics that we can quote to cite progress in these areas, and progress in these areas doesn't immediately translate to record breaking shots.

For example, it is imperative that a disruption will not break ITER (or a future reactor). Our ability to build a disruption mitigation system doesn't allow current experiments to operate longer, hotter, or at higher density.

 

[Donald Jasby]

Fusion device performance is measured by the “confinement triple product” n*tau*Ti , and by fusion energy gain Q = fusion power/ heating power for MCF, or Q = (fusion energy)/ (injected energy on target) for ICF.

As for MCF, there has been zero increase in the triple product or Q since the TFTR and JET results of 1995 to 1997 (20 years ago). No other tokamak has reproduced these results.

As for ICF, two years ago NIF reached Q = 1%, about a factor of 10 higher than the value of 0.1% reached in the early 1990’s at Rochester and Livermore.

The W7-X stellarator plasma parameters are no better than those of tokamaks of the early 1980’s (if that), and W7-X has produced no fusion neutrons.

 

[mfb]

Well, it would be very surprising if ITER does not improve those values. The plan is to be at least 1.5 orders of magnitude above the current records. 30-35 years instead of 15 years later, but if ITER reaches that goal it is very close to reactor conditions. Q=10 is planned.

Wendelstein 7-X is not designed to run with tritium - there would be no point in it. It is used to study the plasma. If it works well and shows that we can control the magnetic field and plasma that way, DEMO might become a stellarator.

 

[phyzguy]

As for ICF, two years ago NIF reached Q = 1%, about a factor of 10 higher than the value of 0.1% reached in the early 1990’s at Rochester and Livermore.

It's true this is an improvement, but I think people who follow this, including the researchers at Livermore, were disappointed that the most recent experiments did not achieve ignition. After all, it is called the NIF for a reason.

 

[Donald Jasby]

Re: mfb comment

With regard to W7-X, I was not referring to tritium, but rather to deuterium.

W7 -X has reported no D-D neutrons. (And neither have most stellerators.) They may have used deuterium and produced embarrasingly low neutron output.

 

[mfb]

They used regular hydrogen (¹H). A neutron flux would have been very surprising. Deuterium is planned for the future.

They are also not at the design values yet, the reactor will need a few upgrades for that.

 

[Astronuc]

14 December 2016
http://www.world-nuclear-news.org/NN-Korean-fusion-reactor-achieves-record-plasma-1412164.html

The Korean Superconducting Tokamak Advanced Research (KSTAR) tokamak-type nuclear fusion reactor has achieved a world record of 70 seconds in high-performance plasma operation, South Korea's National Fusion Research Institute (NFRI) has announced.

The institute, based at Daejeon, 160 km south of Seoul, said a fully non-inductive operation mode - called a "high poloidal beta scenario" - has been used to achieve this long and steady state of operation using high-power neutral beam. It said various techniques, including a rotating 3D field, have been applied to alleviate the accumulated heat fluxes on the plasma-facing components.

https://fusion.gat.com/global/KSTAR

 

[Donald Jasby]

Re: KSTAR post

How much fusion power (ie., neutron production) did this so-called “fusion reactor” actually generate during its 70-sec discharges?

Apparently ZERO. No neutrons are mentioned. And neither is there any mention of density, temperature, confinement time or anything at all,
except 1) the pulse length is 70 sec, and therefore 2) a fusion power reactor is just around the corner (as usual).

Guess what? Plasma arc discharges have operated in the steady state for a century! Presumably, KSTAR has a hotter plasma (who knows?) but at much lower density.

 

[Astronuc]

According to the Wikipedia page, the KSTAR plasma achieved 50 million K. No mention of pressure, plasma density or type of fuel.
https://en.wikipedia.org/wiki/KSTAR (See Timeline)

I've looked at several sites, and other than the 70 ms period, there is little else. I find it disconcerting that press releases and reports don't provide the basic parameters, such a fuel, plasma density and pressure.

The MIT press release on Alcator C-Mod was somewhat more detailed.
http://phys.org/news/2016-10-alcator-c-mod-tokamak-nuclear-fusion.html

While setting the new record of 2.05 atmospheres, a 15 percent improvement, the temperature inside Alcator C-Mod reached over 35 million degrees Celsius, or approximately twice as hot as the center of the sun. The plasma produced 300 trillion fusion reactions per second and had a central magnetic field strength of 5.7 Tesla. It carried 1.4 million amps of electrical current and was heated with over 4 million Watts of power. The reaction occurred in a volume of approximately 1 cubic meter (not much larger than a coat closet) and the plasma lasted for two full seconds.

Read more at: http://phys.org/news/2016-10-alcator-c-mod-tokamak-nuclear-fusion.html#jCp

Some earlier success with KSTAR
http://www-pub.iaea.org/mtcd/meetings/PDFplus/2010/cn180/cn180_papers/ftp_p6-09.pdf

An overview of KSTAR results (published 2013)
http://iopscience.iop.org/article/10.1088/0029-5515/53/10/104005/