Observation of runaway electron beams by visible color camera in the Experimental Advanced Superconducting Tokamak

Shi, Yuejiang; Fu, Jia; Li, Jiahong; Yang, Yu; Wang, Fudi; Li, Yingying; Zhang, Wei; Wan, Baonian; Chen, Zhongyong

doi:10.1063/1.3340909

Cited by 18 publications

(17 citation statements)

References 30 publications

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“…(53) and 50cm, respectively. The toroidal magnetic fields of these three tokamaks are about 5T , 2T and 2T [30][31][32]. The estimation of d 2 ∼ 26cm is comparable to any minor radii listed above.…”

Section: Phase-space Dynamics Of Runaway Electronssupporting

confidence: 49%

Phase-space dynamics of runaway electrons in tokamaks

Guan¹,

Qin²,

Fisch³

2010

Physics of Plasmas

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The phase-space dynamics of runaway electrons is studied, including the influence of loop voltage, radiation damping, and collisions. A theoretical model and a numerical algorithm for the runaway dynamics in phase space are developed. Instead of standard integrators, such as the Runge-Kutta method, a variational symplectic integrator is applied to simulate the long-term dynamics of a runaway electron. The variational symplectic integrator is able to globally bound the numerical error for arbitrary number of time-steps, and thus accurately track the runaway trajectory in phase space. Simulation results show that the circulating orbits of runaway electrons drift outward toward the wall, which is consistent with experimental observations. The physics of the outward drift is analyzed. It is found that the outward drift is caused by the imbalance between the increase of mechanical angular momentum and the input of toroidal angular momentum due to the parallel acceleration. An analytical expression of the outward drift velocity is derived. The knowledge of trajectory of runaway electrons in configuration space sheds light on how the electrons hit the first wall, and thus provides clues for possible remedies.

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Section: Phase-space Dynamics Of Runaway Electronssupporting

confidence: 49%

Phase-space dynamics of runaway electrons in tokamaks

Guan¹,

Qin²,

Fisch³

2010

Physics of Plasmas

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“…A similar shape was observed in visible light for startup runaways in EAST. 11 In shot 146704 shown in Fig. 6, an unknown instability (which occurs after the time shown in the figure) causes the crescent to suddenly change to an oval shape on a timescale of approximately 100 ls.…”

Section: Runaway Images In the Visible Spectral Regionmentioning

confidence: 98%

“…7 REs have been studied previously on a number of tokamaks. 8 Imaging in particular was a key diagnostic in the following cases: during massive gas injection (MGI) experiments using IR synchrotron emission at TEXTOR, 9,10 during plasma startup using visible synchrotron emission at EAST, 11 and during disruptions using soft x-ray (SXR) tomography at JET 12 and using visible emission at HL-2A. 13 Here, we present the first visible light images of synchrotron emission from REs generated during Ar pellet-induced disruptions in DIII-D, 14 and we show visible spectra during the RE current plateau.…”

Section: Introductionmentioning

confidence: 99%

Visible imaging and spectroscopy of disruption runaway electrons in DIII-D

Hollmann

Commaux

et al. 2013

Physics of Plasmas

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The first visible light images of synchrotron emission from disruption runaway electrons are presented. The forward-detected continuum radiation from runaways is identified as synchrotron emission by comparing two survey spectrometers and two visible fast cameras viewing in opposite toroidal directions. Analysis of the elongation of 2D synchrotron images of oval-shaped runaway beams indicates that the velocity pitch angle v ? =v jj ranges from 0.1 to 0.2 for the detected electrons, with energies above 25 MeV. Analysis of synchrotron intensity from a camera indicates that the tail of the runaway energy distribution reaches energies up to 60 MeV, which agrees with 0D modeling of electron acceleration in the toroidal electric field generated during the current quench. A visible spectrometer provides an independent estimate of the upper limit of runaway electron energy which is roughly consistent with energy determined from camera data. Synchrotron spectra reveal that approximately 1% of the total post-thermal quench plasma current is carried by the detected high-energy runaway population with energies in the range of 25-60 MeV; the bulk of the plasma current thus appears to be carried by relativistic electrons with energy less than 25 MeV. In addition to stable oval shapes, runaway beams with other shapes and internal structure are sometimes observed. V C 2013 AIP Publishing LLC [http://dx.

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“…While this approach has been applied with considerable success [8], it has been demonstrated that multiple distributions can be fit to a single spectrum [9]. In an effort to provide additional constraints to the distribution function, filtered 2D visible imaging has been employed on multiple devices [4,7,[10][11][12][13][14][15]. The downside of using camera images is the loss of spectral information.…”

Section: Introductionmentioning

confidence: 99%

Tomographic reconstruction of the runaway distribution function in TCV using multispectral synchrotron images

Wijkamp¹,

Perek²,

Decker³

et al. 2021

Nucl. Fusion

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Observation of runaway electron beams by visible color camera in the Experimental Advanced Superconducting Tokamak

Cited by 18 publications

References 30 publications

Phase-space dynamics of runaway electrons in tokamaks

Phase-space dynamics of runaway electrons in tokamaks

Visible imaging and spectroscopy of disruption runaway electrons in DIII-D

Tomographic reconstruction of the runaway distribution function in TCV using multispectral synchrotron images

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