Abstract
An Advanced Research Projects Agency-Energy funded diagnostic system has been deployed to the Princeton field-reversed configuration 2 (PFRC-2) device, located at Princeton Plasma Physics Laboratory. The Portable Diagnostic Package (PDP), designed at Oak Ridge National Laboratory, allows for the measurement of Thomson Scattering (TS) for electron density and temperature and Optical Emission Spectroscopy (OES) for ion temperature, impurity density, and ion velocity. A tunable spectrometer on the PDP with three gratings provides the flexibility to measure low (1 eV) and high (1000 eV) electron temperature ranges from TS. Additionally, using a second spectrometer, the OES diagnostic can survey light emission from various ion excitation levels for wide wavelength ranges. The electron density (<2 × 1019 m-3) of plasmas generated in PFRC-2 has been below the PDP TS discrimination threshold, which has made TS signal detection challenging against a high-background of laser stray light. The laser stray light was iteratively reduced by making modifications to the entrance and exit geometry on PFRC-2. Rayleigh scattering experiments on PFRC have yielded the TS discrimination sensitivity to be >1 × 1020 m-3 for the PDP. A recently implemented narrow-band notch spectral filter that masks the second harmonic 532 nm Nd:YAG laser wavelength has increased the system's TS light discrimination sensitivity 65 times compared to the instance when the notch filter was not implemented. The hardware implementation including design changes to the flight tubes and Brewster windows will be discussed, along with results from Rayleigh and rotational Raman scattering sensitivity analyses, which were used to establish a quantitative figure of merit on the system performance. The Raman scattering calibration with the notch filter has improved the PDP electron density threshold to 1 ± 0.5 × 1018 m-3.
Original language | English |
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Article number | 113506 |
Journal | Review of Scientific Instruments |
Volume | 93 |
Issue number | 11 |
DOIs | |
State | Published - Nov 1 2022 |
Bibliographical note
Publisher Copyright:© 2022 Author(s).
Funding
http://energy.gov/downloads/doe-public-access-plan This pro-ject was supported by the U.S. Department of Energy, Contract No. D.E.-AC05-00OR22725. The authors acknowledge the Program in Plasma Science and Technology for support under DOE Contract No. D.E.-AC02-09CH11466. The authors also greatly appreciate the funding support provided by the Advanced Research Projects Agency-Energy (ARPA-E).
Funders | Funder number |
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U.S. Department of Energy | D.E.-AC02-09CH11466, D.E.-AC05-00OR22725 |
Advanced Research Projects Agency - Energy |