Synchrotron radiation intensity and energy of runaway electrons in EAST tokamak

Abstract

A detailed analysis of the synchrotron radiation intensity and energy of runaway electrons is presented for the Experimental Advanced Superconducting Tokamak (EAST). In order to make the energy of the calculated runaway electrons more accurate, we take the Shafranov shift into account. The results of the analysis show that the synchrotron radiation intensity and energy of runaway electrons did not reach the maximum at the same time. The energy of the runaway electrons reached the maximum first, and then the synchrotron radiation intensity of the runaway electrons reached the maximum.We also analyze the runaway electrons density, and find that the density of runaway electrons continuously increased. For this reason, although the energy of the runaway electrons dropped but the synchrotron radiation intensity of the runaway electrons would continue rising for a while.

Observation of trapped and passing runaway electrons by infrared camera in the EAST tokamak*

“…Synchrotron radiation images of passing runaway electrons have been observed in many tokamaks, such as EAST, [15] KSTAR, [16][17][18] C-Mod, [2] and DIII-D. [19][20][21][22] The position and orientation of the infrared camera on EAST are described in Ref. [9]. The synchrotron radiation images of passing runaway electrons observed in these devices are generally consistent with the theoretical prediction of Pankratov in Ref.…”

“…So the energy of the runaway electron is E = δ ecB/q. [9] According to the geometry of Fig. 9, we estimate the average shift at δ = 5.56 cm.…”

“…Synchrotron radiation is a powerful tool to infer the parameters of high energy runaway electrons, and the radiation diagnostic system can provide direct images of the distribution of the runaway electrons inside the plasma. [7] In EAST, the synchrotron radiation emitted by runaway electrons is mostly infrared [8,9] It is much easier to observe synchrotron radiation images with an infrared camera than with a visible camera. The synchrotron radiations of almost all shots can be observed by infrared camera, while visible camera can observe the radiations only when the runaway electron radiation is very strong.…”

Calculation of collisionless pitch-angle scattering of runaway electrons with synchrotron radiation via high-order guiding-centre equation

“…The energy of the RE is close to several tens to hundreds of MeV. Attention should be paid to the following points: the relativistic effect is significant; the radiation reaction (Finken, Watkins & Rusbüldt 2011;del Castillo-Negrete et al 2018;Hoppe et al 2018;Zhang, Zhou & Hu 2018 is important; when the inductive electric field becomes strong enough, the runaway avalanche (Nilsson et al 2015;Svensson et al 2021) develops after the thermal quench. Without proper control, these energetic REs will eventually hit the first wall of the device in a localized manner, posing a serious threat to the safe operation of the device.…”

“…2018; Hoppe et al. 2018; Zhang, Zhou & Hu 2018, 2021) is important; when the inductive electric field becomes strong enough, the runaway avalanche (Nilsson et al. 2015; Svensson et al.…”