KSTAR Stability Analysis

The stability map for the KSTAR geometry is generated. The base equilibrium parameters in TOQ are the following:

rmax=47.000000
rzero=177.000000
eshape=2.00
xshape=.64000
totcur=600000.000000
baxis0=20000.000000

The base temperature and density profiles were set using parametric expressions in TOQ using the following parameters:

modelp=27
nedge13=0.7
nped13=2.0
ncore13=5.7
nfactor=1.0
tedgeEV=100.
tpedEV= 500.0
tcoreEV=2000.
widthp=.03
xphalf=.97

The corresponding density profile has the following shape:

The electron density profile

The stability map is generated by varying the nped13, tpedEV and cboot parameters the ranges [0.6:5.5], [100:1600], and [0.1:9] correspondingly. Over 150 new equilibria have been generated. The pedestal stability in these equilbria were tested using the DCON and BALOO codes. The resulting stability map is shown below:

j-alpha stability diagram for KSTAR

j-alpha stability diagram for KSTAR

Here alpha is the normalized plasma pressure gradient defined as

alpha = -displaystyle{frac{mu_0}{2pi^2} frac{partial p}{partial psi} frac{partial V}{partial psi} sqrt{frac{V}{2pi^2 R}}},

where p is the plasma pressure, psi is the poloidal flux, V is the plasma volume, and R is the plasma major radius.

The results are valid for a particular choice of plasma parameters such as I_{rm pl}=0.6 MA, B_{rm T}=2.0 T, kappa=2, and delta=0.64. The plasma shaping is defined according to the Bondeson’s Dee Formula. The pedestal width has been also fixed in my scan and it has been set to 0.6. The location of the H-mode pedestal top for density and temperature profiles was set to 0.94 of the normalized poloidal flux.