Direct Observation of Runaway

Electron Beams in EAST

Yuejiang Shi

Baonian Wan, Jia Fu, Huixian Gao, Fudi Wang, Jiahong Li, and EAST team

Institute of Plasma Physics, Chinese Academy of Sciences,China

ASIPP

4th US-PRCMagnetic Fusion Collaboration Workshop

5-6 May 2008, Austin, Texas, USA

EAST

Self-Introduction

I am the leader of the advanced spectroscopy diagnostic group for HT-

7 and EAST. This group includes charge exchange recombination

spectroscopy (collaboration with FRC_UT),UV-VIS OMA Spectrometer

for impurity measurement, and X-ray Imaging Crystal Spectrometer

(collaboration with PPPL and KSTAR). Main interesting are LHCD

physics, the thermal transport of plasma, the impurity transport in

plasma.

EAST

Outline I. Synchrotron radiation of the

runaway electrons in tokamaks

II. Experimental setup

III. Experimental results

IV. Summary

EAST

Synchrotron radiation spectra of the runaway electrons

The spectra of runaways with different energy

EAST

I. Synchrotron radiation of the runaway electrons in tokamaks

The spectra of runaways with different pitch angle

The profiles of radiation power measured with XUV array

The radiation patterns with different q and fixed pitch angle(p = 0).

EAST

I. Synchrotron radiation of the runaway electrons in tokamaks

Numerical simulated synchrotron patterns of the runaway beams

The radiation pattern with p = 0.06. A parabolic-like q profile is assumed

Two color (RGB) cameras

Wavelength range:380nm-750nm

Sampling frequency:75fps

Pixel number:640480

Appointed purpose in EAST:

Monitor discharge status and plasma shape

EAST

II. Experimental setup

Video of the camera

The relation between the runaway energy and the ratios of the three color pixels. The shading bar are corresponded to the experimental data. Simulation of test particle dynamic equation:,……Elim=47~49MeV, p =0.06~0.07 for Te=0.5keV

Elim=21~432MeV, p =0.1~0.13 for Te=0.7keV …………………….

EASTIII. Experimental results(1)

Typical image in a circular-configuration shot

Waveforms of the discharge in EAST

From this image,

p and q(0) are estimated as 0.06 and

2.8, respectively

EASTIII. Experimental results(2)

The shell pattern of synchrotron radiation in EAST

The shell is located around q=1 surface

The shell is asymmetry in HFS and LFS

IV. Summary It is the first time to observe the synchrotron

radiation emitted from runaway electrons with a common visible camera in EAST tokomak. Very clear synchrotron radiation images from runaway electron beams have been obtained in EAST tokamak. Both the pitch angle and energy limit runaway electrons have been self-consistent derived from the measurement of synchrotron radiation. The experimental results are partly consistent with the test particle dynamics numerical simulation. A strange stable shell shape of synchrotron radiation can be observed. The mechanism for the formation of this shell is unclear.

EAST