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Model Options for tex2html_wrap_inline275 shear stabilization

The original GLF23 model described in the 1996 Waltz paper [1] uses the flux-surface-averaged tex2html_wrap_inline275 shear rate tex2html_wrap_inline323 in circular geometry with a multiplier of tex2html_wrap_inline325. Here, vE is the tex2html_wrap_inline275 shear velocity equal to tex2html_wrap_inline331. Since then it was discovered that the tex2html_wrap_inline275 rate can often exceed the maximum linear growth rate in the outer half of the plasma leading to the formation of an unphysical transport barrier. This was remedied by using a real geometry extension of tex2html_wrap_inline291 where the toroidal field in vE is replaced by tex2html_wrap_inline339 [2]. Here, the factor tex2html_wrap_inline341 typically rises to 2-3 in the outer half of elongated plasmas, thus reducing the tex2html_wrap_inline275 rate in that region significantly. The corresponding multiplier for the original (retuned) models is tex2html_wrap_inline345 which has been found to be consistent with recent gyro-kinetic simulations by Waltz. To use the real geometry tex2html_wrap_inline275 shear, set bt_flag=1 in the namelist input. The effective B-field is computed internally in subroutine callglf2d.f.

Thu Feb 20 11:20:39 EST 2003