Author: Linda Sugiyama
Requested Type: Poster
Submitted: 2022-03-04 13:07:34
Bldg. 26-557, 77 Massachusetts
Cambridge, MA 02139
Pulsed plasma discharges remain an important part of
the planned development of Deuterium-Tritium tokamak
fusion reactors with high magnetic field,
including those that use high temperature superconducting (HTS) magnets. High field tokamaks operate at relatively high plasma current and density. They require initial ramps of current and density up to burning levels, usually with simultaneous plasma size and shape, and perhaps major radius and B_T, evolution.
1 1/2D transport code studies show that this phase is dynamic, with
evolving plasma profiles that differ from the final burning state.
Most of the plasma current is introduced at the edge of the plasma
and diffuses inward. Density is also added to the edge at low temperature. Thus, the off-axis ohmic heating can be substantial.
The DT ideal ignition temperature occurs during the ramp, at the point when the DT alpha-particle heating overtakes the power lost to bremsstrahlung radiation
(locally T_I = 4 keV or peak T_I(0)=6 keV for typical profiles).
Modern tokamaks regularly use varying current and density ramps, but optimization for plasma burning is little studied.
Some important questions remain; their solution may require experimental results from burning plasmas. These issues are discussed.