Measurements of runaway electron synchrotron spectra at high magnetic fields in Alcator C-Mod

Tinguely, R. A.; Granetz, R. S.; Hoppe, M.; Embréus, O.

doi:10.1088/1741-4326/aac444

Title: Measurements of runaway electron synchrotron spectra at high magnetic fields in Alcator C-Mod

Journal Article · Mon Jun 04 00:00:00 EDT 2018 · Nuclear Fusion

DOI:https://doi.org/10.1088/1741-4326/aac444· OSTI ID:1540543

^[1]; Granetz, R. S. ^[1];

^[2]; Embréus, O. ^[2]

Massachusetts Institute of Technology (MIT), Cambridge, MA (United States). Plasma Science and Fusion Center
Chalmers University of Technology, Gothenburg (Sweden)

We report in the Alcator C-Mod tokamak, runaway electron (RE) experiments have been performed during low density, flattop plasma discharges at three magnetic fields: 2.7, 5.4, and 7.8 T, the last being the highest field to-date at which REs have been generated and measured in a tokamak. Time-evolving synchrotron radiation spectra were measured in the visible wavelength range (λ ≈ 300 –1000 nm) by two absolutely-calibrated spectrometers viewing co- and counter-plasma current directions. In this paper, a test particle model is implemented to predict momentum-space and density evolutions of REs on the magnetic axis and q = 1, 3/2, and 2 surfaces. Drift orbits and subsequent loss of confinement are also incorporated into the evolution. These spatiotemporal results are input into the new synthetic diagnostic SOFT which reproduces experimentally-measured spectra. For these discharges, it is inferred that synchrotron radiation dominates collisional friction as a power loss mechanism and that RE energies decrease as magnetic field is increased. Additionally, the threshold electric field for RE generation, as determined by hard x-ray and photo-neutron measurements, is compared to current theoretical predictions.

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Research Organization:: Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)

Sponsoring Organization:: USDOE Office of Science (SC), Fusion Energy Sciences (FES); European Research Council (ERC); Swedish Research Council (SRC)

Grant/Contract Number:: FC02-99ER54512; 647121; Dnr 2014-5510

OSTI ID:: 1540543

Journal Information:: Nuclear Fusion, Vol. 58, Issue 7; ISSN 0029-5515

Publisher:: IOP ScienceCopyright Statement

Country of Publication:: United States

Language:: English

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Cited by: 7 works

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Electron runaway in ASDEX Upgrade experiments of varying core temperature Linder, O.; Papp, G.; Fable, E. Journal of Plasma Physics, Vol. 87, Issue 3 https://doi.org/10.1017/s0022377821000416	journal	May 2021
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Tomographic reconstruction of the runaway distribution function in TCV using multispectral synchrotron images Wijkamp, T. A.; Perek, A.; Decker, J. Nuclear Fusion, Vol. 61, Issue 4 https://doi.org/10.1088/1741-4326/abe8af	journal	March 2021
Experimental and synthetic measurements of polarized synchrotron emission from runaway electrons in Alcator C-Mod Tinguely, R. A.; Hoppe, M.; Granetz, R. S. arXiv https://doi.org/10.48550/arxiv.1906.11304	text	January 2019

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