Role of ECRH in potential formation for tandem mirrors

Conference · Wed May 08 04:00:00 EDT 1985

OSTI ID:5598090

Rognlien, T D; Matsuda, Y; Stewart, J J

The axial ion plugging potential in a tandem mirror is produced by electron cyclotron resonance heating (ECRH) applied at two locations in the end mirror cell. A second harmonic (..omega.. = 2..omega../sub c/) resonance is used near the midplane to generate hot electrons which yield an electron potential barrier between center cell electrons and electrons outboard of the end cell midplane. The latter group of electrons is then heated at the fundamental resonance (..omega.. = ..omega../sub c/) on the outboard side of the magnetic well which drives an ion confining potential. Fokker-Planck and Monte Carlo calculations show that such a configuration is achievable, and the scaling obeys a rather simple set of equations. Another aspect of this configuration is the experimental observation that the fundamental heating drives the overall potential of the device relative to the wall to approx. 1 kV. An analytic model predicts this behavior for very strong ECRH. Results are given a numerical study of electron confinement in a mirror cell owing to fundamental heating as the level of the rf electric field, E/sub rf/, is increased. For the second part of the paper, we show that moderate levels of uniformly distributed rf fields, called cavity fields, can result in very hot (>250 keV) tails in the electron distribution as seen in the TMX-U experiment.

• Research Organization: Lawrence Livermore National Lab., CA (USA)
• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 5598090
• Report Number(s): UCRL-92375; CONF-8505130-5; ON: DE85011859
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
700101* -- Fusion Energy-- Plasma Research-- Confinement
Heating
& Production
ECR HEATING
ELECTRIC POTENTIAL
ELECTROMAGNETIC FIELDS
ELECTRON DENSITY
HEATING
HIGH-FREQUENCY HEATING
MAGNETIC MIRRORS
OPEN PLASMA DEVICES
PLASMA HEATING
PLUGGING
TANDEM MIRRORS
THERMONUCLEAR DEVICES