Evolution of low-density Thomson scattering on EBT

Conference · Sun Jan 01 04:00:00 EST 1984

OSTI ID:6536199

Cobble, J A

The ELMO Bumpy Torus (EBT) confines a low-density, steady-state, microwave-driven plasma. On the basis of favorable initial diagnostic results, major machine upgrades - increases in microwave power and magnetic field - were initiated, and the feasibility of Thomson scattering was considered. From the time of the first laser measurements, in which a two-point spectrum was integrated during 30 or more Q-switched pulses, the Thomson scattering system has evolved into a reliable diagnostic tool that is able to obtain scans along 20 cm of the plasma diameter and to determine the central electron temperature at densities as low as 2 x 10/sup 11/ cm/sup -3/. Based on a 25-J ruby laser and a seven-channel polychrometer, the present system (1) reveals a bulk plasma with T/sub e/ = 20 to 100 eV and n/sub e/ = 5 to 10 x 10/sup 11/ cm/sup -3/ and (2) indicates a suprathermal tail consistent with x-ray measurements. With up to 200 kW of microwave power inside the machine, major problems to overcome were radiation damage to optical materials (less than or equal to 3000 R/h) and plasma coating of windows and dumps.

• Research Organization: Oak Ridge National Lab., TN (USA)
• DOE Contract Number: AC05-84OR21400
• OSTI ID: 6536199
• Report Number(s): CONF-840922-3; ON: DE85001760
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
700102* -- Fusion Energy-- Plasma Research-- Diagnostics
BEAM DUMPS
BUMPY TORI
COATINGS
ELMO BUMPY TORUS
ELMO DEVICES
INELASTIC SCATTERING
MAGNETIC MIRRORS
OPEN PLASMA DEVICES
OPENINGS
PHYSICAL RADIATION EFFECTS
PLASMA DIAGNOSTICS
RADIATION EFFECTS
SCATTERING
THERMONUCLEAR DEVICES
THOMSON SCATTERING
WINDOWS