Tri Alpha talk

[Solo]

Coming to UW-Madison Monday Apr 29:

Prof. Houyang Guo
- Chief experimental strategist of Tri Alpha Energy, Rancho Santa Margarita, CA
- Also professor and director of Tokamak Division Institute of Plasma Physics Chinese Academy of Sciences, Hefei, Anhui, P.R. China

He will give two presentations:
"Progress toward Long Pulse Operation in EAST Superconducting Tokamak"
"Overview of C-2 Compact Toroid Merging Experiments"

Anybody have some intelligent questions they would like me to pose?

[Skipjack]

Yes, me, me, me!
The C2 experiment has recently had some great success with neutral beam injection. How much more do confinement times have to increase to allow for D+T fusion and what are their plans to achieve that? Are they planning to continue the research with C2, or will they move on to a bigger, more powerful device soon?

[Solo]

My notes from the talk:
-150 on staff (!!)
-5ms plasma lifetime, presently limited not by instabilities but by ~1ms confinement time (energy, particles)
-very reproducible discharges despite dynamic merging procedure
-Te ~100eV, Ti ~ 400eV
-20keV beam ions orbit passes through edge, important to keep neutral density down
-plasma guns help stabilize MHD instabilities, other turbulence by biasing & driving anti-rotation
- confinement scales like (Te * r_s)^2 which is very favorable
- planning C-3 device with 100ms-1s confinement times by increased size, heating power

[kurt9]

A staff of 150 people? That's quite a lot. Either Tri-Alpha is on the verge of making it or it has become a bloated bureaucracy. I certainly hope for the former. If so, we should have commercial fusion by the end of the decade - 2020.

I have seen a job advert for a PLC control system engineer, which I have applied for. I did not hear back from them, suggusting they found someone local to do the job (I do not live in SoCal). Nevertheless, I hope they are successful.

[D Tibbets]

My notes from the talk:
-150 on staff (!!)
-5ms plasma lifetime, presently limited not by instabilities but by ~1ms confinement time (energy, particles)
-very reproducible discharges despite dynamic merging procedure
-Te ~100eV, Ti ~ 400eV
-20keV beam ions orbit passes through edge, important to keep neutral density down
-plasma guns help stabilize MHD instabilities, other turbulence by biasing & driving anti-rotation
- confinement scales like (Te * r_s)^2 which is very favorable
- planning C-3 device with 100ms-1s confinement times by increased size, heating power

While I do not follow the significance of all of these numbers, the demonstrated energy confinement time of a few milliseconds is similar to that for the small Polywells (WB6). The question then becomes at what effective densities they are operating at. If at Tokamak densities of 10^19 to 10^20 / M^3 they have a ways to go. If higher densities, they are getting close, at least for D-T fusion. My understanding is that for D-D fusion the confinement times will need to be ~ 100 times longer (at the same density), and the temperatures will need to be higher relative to D-T fusion.

The electron and ion average (?) temperatures seem unimpressive though, assuming I am reading them right. If the plasma is thermalized, the lower electron temperatures relative to the ion temperatures, may be beneficial from a Bremsstruhlung perspective.

Dan Tibbets

[kcdodd]

What density?

[Solo]

I didn't catch the density from his talk, but looking at their paper, which has most of the same content, it's about 4e19/m^3.

The temperatures are thermal. They have a Doppler spectrometer (Ti) and a Thomson Scattering (Te) system. There will of course be a high-energy tail for the ions due to the NBI.

To put these numbers in perspective, MST runs ~1e19/m^3, 200-600eV Te, Ti similar, confinement times about 1ms.

Also, the paper notes that increasing the mirror ratio does not improve the confinement time, which implies that most of the confinement is being done by the FRC itself, which is good to hear.

[Stubby]

http://www.smartplanet.com/blog/bulleti ... ject/19039

same old same old new website

most everyone except emc2 mentioned