Multipass/multipulse Thomson scattering on CDX-U (abstract)

Journal Article · Wed Jan 01 04:00:00 EST 1997 · Review of Scientific Instruments

DOI:https://doi.org/10.1063/1.1147674· OSTI ID:451836

Stutman, D; Hwang, Y S; Menard, J; Choe, W; Ono, M ^[1]; Petrov, Y; Gusev, V; Mukhin, E ^[2]

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1. Princeton Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543 (United States)
2. Ioffe Institute, St. Petersburg (Russia)

A multipass/multipulse Thomson scattering system has been implemented on CDX-U in collaboration with the Ioffe Institute, St. Petersburg. The system consists of a low energy (1.5{endash} 2.5 J), passively Q-switched ruby laser, and a multipass optical cavity enclosing the plasma. Multiple reflections of the beam within the cavity increase by about an order of magnitude the number of scattered photons, allowing temperature density to be measured with good accuracy even at very low plasma density. By feeding the returned beam back into the laser, the system can deliver several pulses over a 1 ms period. However, the experiments on CDX-U show that a mechanical shock wave reaching the multipass system affects the feedback and laser output per pulse drops significantly. Therefore we operate the system by fine tuning the laser cavity, so that output is practically independent of feedback from multipass cavity. Also, by optimizing the transmission of the passive Q-switch and the pumping power, we obtain that laser output is concentrated in single large pulse of 2{endash}2.5 J energy. We achieve circulating energy in the plasma in excess of 12 J per pulse, while minimizing at the same time stray light. As shown by results from CDX-U, this enables in some cases better than 10{percent} accuracy, despite relatively low plasma density conditions. {copyright} {ital 1997 American Institute of Physics.}

• OSTI ID: 451836
• Report Number(s): CONF-960543--
• Journal Information: Review of Scientific Instruments, Journal Name: Review of Scientific Instruments Journal Issue: 1 Vol. 68; ISSN 0034-6748; ISSN RSINAK
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
LASER CAVITIES
LASER RADIATION
LIGHT SCATTERING
LINEAR Z PINCH DEVICES
OPERATION
PINCH EFFECT
PLASMA DENSITY
PLASMA DIAGNOSTICS
THOMSON SCATTERING
TOKAMAK DEVICES
Z pinch
measurement by laser beam
plasma temperature