Electron confinement in a bumpy torus without the influence of hot-electron rings: ''Ring killer'' experiment

Journal Article · Sun Sep 01 04:00:00 EDT 1985 · Phys. Fluids; (United States)

DOI:https://doi.org/10.1063/1.865205· OSTI ID:5293311

Hillis, D L; Wilgen, J B; Cobble, J A; Davis, W A; Hiroe, S; Rasmussen, D A; Richards, R K; Uckan, T; Jaeger, E F; Hankins, O E

The ELMO Bumpy Torus (EBT) (Plasma Physics and Controlled Nuclear Fusion (IAEA, Vienna, 1975), Vol. II, p. 141) normally has an energetic electron ring in each of its 24 mirror sectors. The original intention of using this hot-electron population was to provide an average local minimum in the magnetic field (through its diamagnetism) to stabilize the simple interchange and flute modes, which otherwise are theoretically inherent in a closed-field-line bumpy torus. To study the confinement properties of a bumpy torus without the influence of hot-electron rings, a water-cooled stainless steel limiter in each mirror sector was extended into the plasma to the ring location; this eliminated the hot-electron ring population. These limiters were aptly named ''ring killers.'' Electron temperature, density, space potential, and plasma fluctuations have been measured during the ring killer experiment and are compared to standard EBT operation. The results of these experiments indicate that the hot-electron rings in EBT do enhance the core plasma properties of EBT and do, in fact, reduce plasma fluctuations; however, these improvements are not large in magnitude. These measurements and recent theoretical models suggest that simple interchange/flute modes are stabilized, or fluctuation levels reduced, well before that condition is obtained for average minimum-B stabilization.

• Research Organization: Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831
• DOE Contract Number: AC05-84OR21400
• OSTI ID: 5293311
• Journal Information: Phys. Fluids; (United States), Journal Name: Phys. Fluids; (United States) Vol. 28:9; ISSN PFLDA
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
700101* -- Fusion Energy-- Plasma Research-- Confinement
Heating
& Production
700102 -- Fusion Energy-- Plasma Research-- Diagnostics
ANTENNAS
BEAMS
BUMPY TORI
CONFINEMENT
CORRELATIONS
ELECTRIC PROBES
ELECTRICAL EQUIPMENT
ELECTRON RINGS
ELECTRON TEMPERATURE
ELMO BUMPY TORUS
ELMO DEVICES
EQUIPMENT
FLUCTUATIONS
HOT PLASMA
INELASTIC SCATTERING
INTERFEROMETERS
ION BEAMS
ION PROBES
LANGMUIR PROBE
LASERS
MAGNETIC MIRRORS
MEASURING INSTRUMENTS
OPEN PLASMA DEVICES
PLASMA
PLASMA CONFINEMENT
PLASMA DENSITY
PLASMA DIAGNOSTICS
POTENTIALS
PROBES
RUBY LASERS
SCATTERING
SOLID STATE LASERS
THERMONUCLEAR DEVICES
THOMSON SCATTERING
VARIATIONS