Microstability of the TMX tandem mirror experiments

Conference · Sat Aug 01 00:00:00 EDT 1987

OSTI ID:6261682

Casper, T A; Berzins, L V

In the tandem mirror device, an efficient source of warm ions, the central cell, is available for stabilization of ion loss-cone instabilities. These instabilities previously limited ion confinement in single-cell mirror experiments. In the simple tandem mirror device, TMX, the drift cyclotron loss-cone (DCLC) mode was stabilized by plasma flow from the central cell into the end cell. However, to enhance the central-cell confinement and provide MHD stability, neutral beams were injected perpendicular to the magnetic field, which resulted in the excitation in the end cell of the Alfven ion-cyclotron (AIC) instability driven by plasma pressure and velocity distribution anisotropy. In the thermal-barrier experiment, TMX-U, the end-cell beams were injected at a 45/sup 0/ angle to the magnetic field to produce a sloshing-ion distribution, which is required to form the thermal barrier and the plugging potential. Ion distributions created by oblique injection were stable to the AIC mode and to the midplane (minimum magnetic field location) DCLC mode. However, an ion loss-cone instability remained at an axial location just outside the outboard peak of the sloshing-ion axial density profile, which is the density peak closest to the end wall. This mode can enhance the sloshing-ion loss rate, particularly at the lower levels of electron-cyclotron resonance heating (ECRH) used to form the thermal barrier. The stability to ion-cyclotron modes is critical to the performance of tandem mirrors and to designs for a mirror-based, high-fluence neutron source.

• Research Organization: Lawrence Livermore National Lab., CA (USA)
• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 6261682
• Report Number(s): UCRL-96668; CONF-870908-2; ON: DE87014356
• Resource Relation: Conference: Course and workshop on physics of mirrors, reversed field pinches and compact tori, Varenna, Italy, 1 Sep 1987; Other Information: Portions of this document are illegible in microfiche products
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
TMX DEVICES
LOSS CONE INSTABILITY
PLASMA MICROINSTABILITIES
COMPARATIVE EVALUATIONS
FLUCTUATIONS
ION CYCLOTRON-RESONANCE
NEUTRON SOURCES
STABILITY
CYCLOTRON RESONANCE
INSTABILITY
MAGNETIC MIRRORS
OPEN PLASMA DEVICES
PARTICLE SOURCES
PLASMA INSTABILITY
RADIATION SOURCES
RESONANCE
TANDEM MIRRORS
THERMONUCLEAR DEVICES
VARIATIONS
700107* - Fusion Energy- Plasma Research- Instabilities