Infrared laser diagnostics for ITER

Conference · Sun Dec 31 04:00:00 EST 1995

OSTI ID:195690

Hutchinson, D P; Richards, R K; Ma, C H

Two infrared laser-based diagnostics are under development at ORNL for measurements on burning plasmas such as ITER. The primary effort is the development of a CO{sub 2} laser Thomson scattering diagnostic for the measurement of the velocity distribution of confined fusion-product alpha particles. Key components of the system include a high-power, single-mode CO{sub 2} pulsed laser, an efficient optics system for beam transport and a multichannel low-noise infrared heterodyne receiver. A successful proof-of-principle experiment has been performed on the Advanced Toroidal Facility (ATF) stellerator at ORNL utilizing scattering from electron plasma frequency satellites. The diagnostic system is currently being installed on Alcator C-Mod at MIT for measurements of the fast ion tail produced by ICRH heating. A second diagnostic under development at ORNL is an infrared polarimeter for Faraday rotation measurements in future fusion experiments. A preliminary feasibility study of a CO{sub 2} laser tangential viewing polarimeter for measuring electron density profiles in ITER has been completed. For ITER plasma parameters and a polarimeter wavelength of 10.6 {micro}m, a Faraday rotation of up to 26{degree} is predicted. An electro-optic polarization modulation technique has been developed at ORNL. Laboratory tests of this polarimeter demonstrated a sensitivity of {le} 0.01{degree}. Because of the similarity in the expected Faraday rotation in ITER and Alcator C-Mod, a collaboration between ORNL and the MIT Plasma Fusion Center has been undertaken to test this polarimeter system on Alcator C-Mod. A 10.6 {micro}m polarimeter for this measurement has been constructed and integrated into the existing C-Mod multichannel two-color interferometer. With present experimental parameters for C-Mod, the predicted Faraday rotation was on the order of 0.1{degree}. Significant output signals were observed during preliminary tests. Further experiment and detailed analyses are under way.

• Research Organization: Oak Ridge National Lab., TN (United States)
• Sponsoring Organization: USDOE, Washington, DC (United States)
• DOE Contract Number: AC05-84OR21400
• OSTI ID: 195690
• Report Number(s): CONF-950848--4; ON: DE96004565
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
ALCATOR DEVICE
ATF TORSATRON
CARBON DIOXIDE LASERS
ELECTRON DENSITY
FEASIBILITY STUDIES
FUSION YIELD
INFRARED RADIATION
INTERFEROMETERS
ITER TOKAMAK
PERFORMANCE TESTING
PLASMA DIAGNOSTICS
POLARIMETERS
THOMSON SCATTERING