Conversion of magnetic energy to runaway kinetic energy during the termination of runaway current on the J-TEXT tokamak

Dai, A.J.; Chen, Z Y; Huang, Dan; Tong, R. H.; Zhang, J; Wei, Yunong; Wang, X L; Yang, Hui; Gao, Hua; Pan, Yuan

doi:10.1088/1361-6587/aab16d

Cited by 11 publications

(5 citation statements)

References 30 publications

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“…MHD modes that develop during the runaway beam phase have been observed exper imentally and predicted numerically for ITER [134] and could lead to high heat loads on first wall components of ITER. Additionally, frequent reoccurrence of such events during the plateau phase can also facilitate high magnetic to kinetic energy conversion factors [269,292]. It has been discussed whether impurity injection into the runaway beam aiming at collisional energy dissipation could trigger such MHD events [12].…”

Section: Other Re Mitigation Techniquesmentioning

confidence: 99%

Physics of runaway electrons in tokamaks

et al. 2019

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Of all electrons, runaway electrons have long been recognized in the fusion community as a distinctive population. They now attract special attention as a part of ITER mission considerations. This review covers basic physics ingredients of the runaway phenomenon and the ongoing efforts (experimental and theoretical) aimed at runaway electron taming in the next generation tokamaks. We emphasize the prevailing physics themes of the last 20 years: the hot-tail mechanism of runaway production, runaway electron interaction with impurity ions, the role of synchrotron radiation in runaway kinetics, runaway electron transport in presence of magnetic fluctuations, micro-instabilities driven by runaway electrons in magnetized plasmas, and vertical stability of the plasma with runaway electrons. The review also discusses implications of the runaway phenomenon for ITER and the current strategy of runaway electron mitigation.

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Section: Other Re Mitigation Techniquesmentioning

confidence: 99%

Physics of runaway electrons in tokamaks

et al. 2019

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“…Secondly, one should question if the approximation of neglecting the macroscopic kinetic energy of the fluid still holds, since runaway electrons have relativistic velocities. Indeed, in [22] the conversion of magnetic energy to runaway electrons kinetic energy is widely discussed, specifically during the termination of runaway current on the J-TEXT tokamak. Finally, generalized Ohm's law may be not valid in its usual form, which means that the quantity P em,u might be not expressed by (18), i.e.…”

Section: Discussion About Simplifying Assumptionsmentioning

confidence: 99%

Energy balance during disruptions

Isernia¹,

Scalera²,

Serpico³

et al. 2020

Plasma Phys. Control. Fusion

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In the operation of tokamaks, hard-to-predict fast transient events, called disruptions, are often responsible for severe energy deposition on the structures surrounding the plasma. In this paper, first of all we derive an overall energy balance for a disruptive plasma, then we use an evolutionary equilibrium code (CarMa0NL) to reproduce the macroscopic plasma evolution during a disruption of a sample high-aspect-ratio circular plasma, analysing the energy fluxes which take place during the event. We show that the variations of toroidal magnetic energy are compensated by one portion of the Poynting vector flux, and that dissipated heat during the Thermal Quench is mainly related to the loss of internal energy. Moreover, we develop an analytical model providing physical insight on the energy deposition on the wall during the Current Quench, related to the poloidal magnetic energy, in a quantity depending on the time scale of the event compared to the electromagnetic time constants.

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“…where a is the minor radius of the plasma, and the width of the runaway current profile DZ curr has been characterized by the full width of the soft x-ray emission profile peak at /e 1 of its maximum. Through this method, the internal inductance l i is about 1.3 in J-TEXT tokamak [44]. Another more important issue for the next-generation device is to confirm the value of 'critical field' E crit for RE generation.…”

Section: Runaway Current Growth Ratementioning

confidence: 95%

Soft landing of runaway currents by ohmic field in J-TEXT tokamak

Hu¹,

Yan²,

Tong³

et al. 2020

Plasma Sci. Technol.

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Recently, experimental studies on the soft landing of RE current by ohmic (OH) field have been performed in J-TEXT tokamak, as a possible auxiliary method to dissipate the RE current. With optimized horizontal displacement control of the RE beam, the toroidal electric field has been scanned from 1.6 to --0.3 V m 1 during the RE plateau phase. The growth rate of RE currents and the evolution of hard x-ray (HXR) emissions have been studied. It is found that when the toroidal electric field is less than 7-12 times the theoretical critical electric field, the decay of REs could be achieved. The dissipation rate by the ohmic field can reach a maximum value of -3 MA s .1 Furthermore, the results of HXR spectra analysis indicate the different behaviors of HXR emissions under the condition of different toroidal electric fields. The analysis of the ionized argon emissions and magnetic fluctuations shows that under the condition of different toroidal electric fields, the physical process of RE generation may be different.

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Conversion of magnetic energy to runaway kinetic energy during the termination of runaway current on the J-TEXT tokamak

Cited by 11 publications

References 30 publications

Physics of runaway electrons in tokamaks

Physics of runaway electrons in tokamaks

Energy balance during disruptions

Soft landing of runaway currents by ohmic field in J-TEXT tokamak

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