Page 1 of 2
Excitement at the Plasma Boundary
Posted: Sun Jan 27, 2013 11:21 pm
by jcoady
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.
Posted: Mon Jan 28, 2013 3:57 pm
by jcoady
Posted: Mon Jan 28, 2013 6:08 pm
by jcoady
Posted: Mon Jan 28, 2013 11:21 pm
by happyjack27
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.
Posted: Tue Jan 29, 2013 12:48 am
by kcdodd
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.
Posted: Tue Jan 29, 2013 5:19 am
by Joseph Chikva
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.
Posted: Tue Jan 29, 2013 5:27 am
by Joseph Chikva
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.
Posted: Tue Jan 29, 2013 8:17 pm
by kcdodd
The idea of liquid lithium surface is interesting. Solves two problems at once.
Posted: Tue Jan 29, 2013 11:24 pm
by happyjack27
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.
Posted: Wed Jan 30, 2013 1:05 am
by KitemanSA
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.
Posted: Thu Jan 31, 2013 12:24 am
by Joseph Chikva
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.
Posted: Thu Jan 31, 2013 12:35 am
by Joseph Chikva
kcdodd wrote:The idea of liquid lithium surface is interesting. Solves two problems at once.
May be. I am not familiar with that idea.
Posted: Thu Jan 31, 2013 1:21 am
by KitemanSA
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.
Posted: Thu Jan 31, 2013 4:33 am
by Joseph Chikva
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.
Posted: Thu Jan 31, 2013 2:05 pm
by KitemanSA
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.