Collisional damping of electron bernstein waves and its mitigation by evaporated lithium conditioning in spherical-tokamak plasmas.
The first experimental verification of electron Bernstein wave (EBW) collisional damping, and its mitigation by evaporated Li conditioning, in an overdense spherical-tokamak plasma has been observed in the National Spherical Torus Experiment (NSTX). Initial measurements of EBW emission, coupled from NSTX plasmas via double-mode conversion to O-mode waves, exhibited <10% transmission efficiencies. Simulations show 80% of the EBW energy is dissipated by collisions in the edge plasma. Li conditioning reduced the edge collision frequency by a factor of 3 and increased the fundamental EBW transmission to 60%.
Diem
S J
SJ
Oak Ridge National Laboratory, Oak Ridge 37831, Tennessee, USA.
Taylor
G
G
Caughman
J B
JB
Efthimion
P C
PC
Kugel
H
H
LeBlanc
B P
BP
Phillips
C K
CK
Preinhaelter
J
J
Sabbagh
S A
SA
Urban
J
J