Publication Date:
2016-08-16
Description:
Heterodyne interferometry and phase contrast imaging (PCI) are robust, mature techniques for measuring low- k and high- k electron density fluctuations, respectively. This work describes the first-ever implementation of a combined PCI–interferometer. The combined system uses a single 10.6 μ m probe beam, two interference schemes, and two detectors to measure electron density fluctuations at large spatiotemporal bandwidth (10 kHz 〈 f 〈 5 MHz and 0 cm -1 ≤ k ≤ 20 cm -1 ), allowing simultaneous measurement of ion- and electron-scale instabilities. Further, correlating our interferometer’s measurements with those from DIII-D’s pre-existing, toroidally separated interferometer allows core-localized, low- n MHD studies that may otherwise be inaccessible via external magnetic measurements. The combined diagnostic’s small port requirements and minimal access restrictions make it well-suited to the harsh neutron environments and limited port space expected in next-step devices.
Print ISSN:
0034-6748
Electronic ISSN:
1089-7623
Topics:
Electrical Engineering, Measurement and Control Technology
,
Physics
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