An experimental determination of the hot electron ring geometry in a Bumpy Torus and its implications for Bumpy Torus stability

Technical Report · Wed Oct 01 04:00:00 EDT 1986

DOI:https://doi.org/10.2172/6936177· OSTI ID:6936177

Hillis, D. L.; Wilgen, J. B.; Bigelow, T. S.; Swain, D. W.; Hankins, O. E.; Juhala, R. E.

The hot electron rings of the ELMO Bumpy Torus (EBT) (Plasma Physics and Controlled Nuclear Fusion (IAEA, Vienna, 1975), Vol. II, p. 141) are formed by electron cyclotron resonance heating (ECRH) and have an electron temperature of 350 to 500 keV. The original intention of these hot electron rings was to provide a local minimum in the magnetic field and, thereby, stabilize the simple interchange and flute modes, which are inherent in a closed field line bumpy torus. To evaluate the electron energy density of the EBT rings and determine if enough stored energy is present to provide a local minimum in the magnetic field, a detailed understanding of the spatial distribution of the rings is imperative. The purpose of this report is to measure the ring thickness and investigate its implications for bumpy torus stability. The spatial location and radial profile of the hot electron ring are measured with a unique metal ball pellet injector, which injects small metallic balls into the EBT ring plasma. From these measurements the radial extent (or ring thickness) is about 5 to 7 cm full width at half maximum for typical EBT operation, which is much larger than previously expected. These measurements and recent modeling of the EBT plasma indicate that the hot electron ring's stored energy may not be sufficient to produce a local minimum in the magnetic field.

• Research Organization: Oak Ridge National Lab., TN (USA)
• DOE Contract Number: AC05-84OR21400
• OSTI ID: 6936177
• Report Number(s): ORNL/TM-9494; ON: DE87004048
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
700103* -- Fusion Energy-- Plasma Research-- Kinetics
BUMPY TORI
ECR HEATING
ELECTRON RINGS
ELECTRON TEMPERATURE
ELMO BUMPY TORUS
ELMO DEVICES
HEATING
HIGH-FREQUENCY HEATING
MAGNETIC MIRRORS
OPEN PLASMA DEVICES
OPERATION
PLASMA HEATING
STABILITY
THERMONUCLEAR DEVICES