Laser calibration of the DIII-D coherence imaging system

Allen, S. L.; Samuell, C. M.; Meyer, W. H.; Howard, J.

doi:10.1063/1.5038739

Laser calibration of the DIII-D coherence imaging system

Journal Article · Wed Sep 26 00:00:00 EDT 2018 · Review of Scientific Instruments

DOI:https://doi.org/10.1063/1.5038739· OSTI ID:1545491

Allen, S. L. ^[1]; Samuell, C. M. ^[1]; Meyer, W. H. ^[1]; ^[2]

Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Australian National Univ., Canberra, ACT (Australia)

Here, we describe an in situ calibration technique for Coherence Imaging Spectroscopy (CIS) that measures 2-D images of ion flows on DIII-D. A low power CW diode laser that is tuneable in the range 464-468 nm along with a precision wavemeter (10^–5 nm resolution) is used to characterize the interferometer phase as a function of wavelength in the region of C _iii (465 nm) and He _ii (468 nm). The interferometer is stabilized both mechanically and thermally to minimize drift during the calibration. Optical stirring and an integration sphere are utilized to obtain spatially uniform calibration images. The quality of the calibration data enables a measurement of phase versus wavelength over approximately 10 fringes of the interferometer. These coefficients can also be related to the geometry of the optics and the birefringent crystal of the interferometer. On DIII-D, the integration sphere with the laser light is inserted into the CIS optical system between shots and the laser image and wavelength are automatically recorded, providing a zero velocity reference

Research Organization:: Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)

Sponsoring Organization:: USDOE National Nuclear Security Administration (NNSA); USDOE Office of Science (SC), Fusion Energy Sciences (FES)

Grant/Contract Number:: AC52-07NA27344; FC02-04ER54698

OSTI ID:: 1545491

Alternate ID(s):: OSTI ID: 1882281

Report Number(s):: LLNL-JRNL-756404

Journal Information:: Review of Scientific Instruments, Journal Name: Review of Scientific Instruments Journal Issue: 10 Vol. 89; ISSN 0034-6748

Publisher:: American Institute of Physics (AIP)Copyright Statement

Country of Publication:: United States

Language:: English

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