一种用于减少汤姆逊散射杂散光的高功率空间滤波器。

A high-power spatial filter for Thomson scattering stray light reduction.

作者信息

Levesque J P, Litzner K D, Mauel M E, Maurer D A, Navratil G A, Pedersen T S

机构信息

Department of Applied Physics and Applied Mathematics, Columbia University, 500 W. 120th Street, New York, New York 10027, USA.

出版信息

Rev Sci Instrum. 2011 Mar;82(3):033501. doi: 10.1063/1.3549142.

DOI:10.1063/1.3549142

PMID:21456731

Abstract

The Thomson scattering diagnostic on the High Beta Tokamak-Extended Pulse (HBT-EP) is routinely used to measure electron temperature and density during plasma discharges. Avalanche photodiodes in a five-channel interference filter polychromator measure scattered light from a 6 ns, 800 mJ, 1064 nm Nd:YAG laser pulse. A low cost, high-power spatial filter was designed, tested, and added to the laser beamline in order to reduce stray laser light to levels which are acceptable for accurate Rayleigh calibration. A detailed analysis of the spatial filter design and performance is given. The spatial filter can be easily implemented in an existing Thomson scattering system without the need to disturb the vacuum chamber or significantly change the beamline. Although apertures in the spatial filter suffer substantial damage from the focused beam, with proper design they can last long enough to permit absolute calibration.

摘要

高β托卡马克-扩展脉冲装置（HBT-EP）上的汤姆逊散射诊断仪通常用于在等离子体放电期间测量电子温度和密度。五通道干涉滤光片多色仪中的雪崩光电二极管测量来自6纳秒、800毫焦、1064纳米钕钇铝石榴石激光脉冲的散射光。为了将杂散激光降低到准确瑞利校准可接受的水平，设计、测试并在激光束线上添加了一种低成本、高功率的空间滤波器。给出了对空间滤波器设计和性能的详细分析。该空间滤波器可以很容易地在现有的汤姆逊散射系统中实现，而无需干扰真空室或显著改变光束线。尽管空间滤波器中的孔径会受到聚焦光束的严重损坏，但通过适当设计，它们可以持续足够长的时间以进行绝对校准。