Excitement at the Plasma Boundary

jcoady · Post by **jcoady** » Sun Jan 27, 2013 11:21 pm

The link below contains a video of a recent talk at PPPL entitled "Excitement at the Plasma Boundary" about ITER plasma boundary issues.

http://www.pppl.gov/events/colloquium-e ... a-boundary

The video player for the embedded video contains a toggle button to allow you to view the video in fullscreen mode.

jcoady · Post by **jcoady** » Mon Jan 28, 2013 3:57 pm

They provide a link to the presentation slides.

http://www.pppl.gov/sites/pppl/files/WC ... ston_0.pdf

jcoady · Post by **jcoady** » Mon Jan 28, 2013 6:08 pm

Here are some press releases from recent APS conference about fusion.

http://www.aps.org/units/dpp/meetings/v ... plasma.pdf

http://www.aps.org/units/dpp/meetings/v ... npower.pdf

http://www.aps.org/units/dpp/meetings/v ... ablobs.pdf

http://www.aps.org/units/dpp/meetings/v ... plasma.pdf

http://www.aps.org/units/dpp/meetings/v ... fusion.pdf

happyjack27 · Post by **happyjack27** » Mon Jan 28, 2013 11:21 pm

problem with iter geometry is that the plasma boundary is inherently unstable. from an engineering perspective that's as good as fail. it's something that should only be considered in the absence of any other tenable options. there are other tenable options.

kcdodd · Post by **kcdodd** » Tue Jan 29, 2013 12:48 am

The problem he is illustrating is not a stability issue. Its high heat flux density on plasma facing surfaces. I have a feeling that will be some issue no matter what.

Joseph Chikva · Post by **Joseph Chikva** » Tue Jan 29, 2013 5:19 am

happyjack27 wrote:problem with iter geometry is that the plasma boundary is inherently unstable.

Again and again - not true.
Stability is a challenge in all plasma device but TOKAMAKs today are the most stable machines providing minutes order confinement time.
That is only the naked fact.

Joseph Chikva · Post by **Joseph Chikva** » Tue Jan 29, 2013 5:27 am

kcdodd wrote:Its high heat flux density on plasma facing surfaces.

If TOKAMAK will become commercial reactor ever, the neutron flux would be more critical for the first wall than heat flux. This is issue for all neutronic machines.
In ITER the combination of beryllium and copper alloy facing materials are used which by idea should withstand to neutrons at acceptable level.

kcdodd · Post by **kcdodd** » Tue Jan 29, 2013 8:17 pm

The idea of liquid lithium surface is interesting. Solves two problems at once.

happyjack27 · Post by **happyjack27** » Tue Jan 29, 2013 11:24 pm

Joseph Chikva wrote:
happyjack27 wrote:problem with iter geometry is that the plasma boundary is inherently unstable.
Again and again - not true.
Stability is a challenge in all plasma device but TOKAMAKs today are the most stable machines providing minutes order confinement time.
That is only the naked fact.

TOKAMAKS are not the most stable configurations, and high confinement time does not imply stability.

KitemanSA · Post by **KitemanSA** » Wed Jan 30, 2013 1:05 am

happyjack27 wrote:TOKAMAKS are not the most stable configurations, and high confinement time does not imply stability.

Don't bother. He is incapable of seeing anything but his beloved toks. Any suggestion that his beloved isn't the most perfect thing since sliced bread brings out his ire which blinds him and blocks him from any ability to receive and understand information.

Joseph Chikva · Post by **Joseph Chikva** » Thu Jan 31, 2013 12:24 am

happyjack27 wrote:...and high confinement time does not imply stability.

If so, please explain what does imply the high confinement time?
For your reference fusion research history is the history of attempts to find stability conditions in satisfying of which long enough confinement is possible.

Joseph Chikva · Post by **Joseph Chikva** » Thu Jan 31, 2013 12:35 am

kcdodd wrote:The idea of liquid lithium surface is interesting. Solves two problems at once.

May be. I am not familiar with that idea.

KitemanSA · Post by **KitemanSA** » Thu Jan 31, 2013 1:21 am

Joseph Chikva wrote:
happyjack27 wrote:...and high confinement time does not imply stability.
If so, please explain what does imply the high confinement time?

Very low beta.

Joseph Chikva · Post by **Joseph Chikva** » Thu Jan 31, 2013 4:33 am

KitemanSA wrote:
Joseph Chikva wrote:
happyjack27 wrote:...and high confinement time does not imply stability.
If so, please explain what does imply the high confinement time?
Very low beta.

Stability and confinement time are in direct dependence.

And yes, unlike all other concepts TOKAMAK theory is better developed.
And there is the so called Troyon limit showing that TOKAMAK machines should run stably at beta<0.4.
In satisfying of this and also some other limits TOKAMAKs are so stable that provide long enough confinement time.

KitemanSA · Post by **KitemanSA** » Thu Jan 31, 2013 2:05 pm

Joseph Chikva wrote:And there is the so called Troyon limit showing that TOKAMAK machines should run stably at beta<0.4.

Which is another way of saying that toks are unstable unless under-driven.

Robthebob,
Here is another interesting potential demo, though I am not sure how much science is here... see how long you can maintain confinement. See if you can run the thing steady state in people scale rather than just in electron scale.