ARIES Physics Group Conference Call

Tuesday 6/23/1998
12:05 EDT -- (9:05 PDT)
call in number: 314-232-7474


1. Discussion of MHD Stability
2. Implications of higher kappa and delta
3. Heating power needed for Startup and profile control
4. Should we come down 10% in beta for "disruption avoidance?"
5. Free boundary Equilibrium
6. Schedule for incorporation in strawman
7. Other physics results

Participating in the Call:

S. Jardin (PPPL)
M. Peng (ORNL)
R. Stambaugh, V. Chan, L. Lao, B. Miller (GA)
R. Miller, T.K. Mau (UCSD)

1. A new strawman was proposed with:

beta = 60%
beta_N = 8.3
kappa = 3.4
delta = 0.65 [note to GA sin(delta)=0.6]
inboard squareness = 0
outboard squareness = 0.0875

Kessel has sent EQDSK to R.Miller

2. Calculations by Menard using the PEST-II code show this is stable to ballooning and kink modes up to n=6 with an ideally conducting wall with a separation of 0.165 a. The consensus is that the ARIES-ST steel first wall (thickness 1.5 cm) and supporting structure will provide the passive stabilization to the kink modes. Neutral beams will provide the rotation needed to stabilize the resistive-wall mode. This is the design assumption, but needs to be quantified that this is adequate for the report.

3. Calculations [by Turnbull?] using the GAT0 code show that the n=0 instability is passively stabilized by a continuous wall at b/a = 1.6 (ie, a separation of 0.6 a). Neither the TEQ code nor the TSC code has yet been able to give results for this case, and so the consensus was to consider it to be vertically controllable, based on the GATO ideal MHD results. Control power requirements still need to be calculated.

4. It was recommended that the design be equipped with 50 MW of 90 kV neutral beam power to provide some current profile control and plasma rotation. T.K. Mau will quantify how much current this can actually provide, but it will probably be in the range 1.7 - 5 % , solely at the edge.

5. Lang Lao will use EFIT to compute free boundary equilibrium for this case. He will work with R.Miller to get possible coil locations.

6. V. Chan will oversee startup calculations addressing how much power is needed for a stable bootstrap-overdrive startup of ARIES-ST.

7. We will keep the date July 24 open [12 noon EDT] for a possible follow-on conference call if significant new results are available to make it desirable. Please contact S.Jardin before this time if you would like to have a conference call.

8. R. Miller posted a PRELIMINARY higher-beta strawman on his web-site at It is called Case A 06/17/98. It was somewhat surprising that the COE didn't come down below 9.5 cents. This is being looked at.