Design and platform testing of the compact torus central fueling device for the EAST tokamak

Abstract

Compact Tours (CT) injection is a highly promising technique for the central fueling of future reactor-grade fusion devices since it features extremely high injection velocity and relatively high plasma mass. Recently, a CT injector for the EAST tokamak, EAST-CTI, was developed and platform-tested. In the first round of experiments conducted with low parameter settings, the maximum velocity and mass of the CT plasma were 150 km·s−1 and 90 µg, respectively. However, the parameters obtained by the EAST-CTI were still very low and were far from the requirements of a device such as the EAST that has a strong magnetic field. In the future, we plan to solve the spark problem that the EAST-CTI currently encounters (that mainly hinders the further development of experiments) through engineering methods and use greater power to obtain a more stable and suitable CT plasma for EAST.

Vacuum-Ultraviolet spectrometer system for impurity emission measurement on a Compact Torus Injection System of EAST

“…The experimental results verify its powerful ability for central fueling and also indicate some other beneficial effects, such as high-confinement mode transition and the mitigation of disruptions [6,7]. Recently, a CTI system was designed and built on experimental advanced superconducting tokamak (EAST), which is a medium-sized tokamak with strong magnetic fields (2 ∼ 3 T) [8,9]. The mass and the maximum velocity of the CTI plasma were 90 μg and 150 km•s −1 , respectively, in the first round experiments.…”

“…The line-averaged electron density was measured by the optical fiber interferometer [31] and about 100-150 × 10 20 m −3 at flat-top stage. The electron temperature is measured by Langmuir probes [8] and relatively low, only around several eV in this round experiment. In the formation region, a high voltage of about 15 kV is generated between the inner electrode and outer electrode to break down the main particle helium, with impurities on the electrodes sputtered out and enter the plasma.…”

“…Where 𝐽 comes from external capacitor bank discharge, and 𝐵 mainly comes from the toroidal magnetic field of CTI [30]. The estimated volume of CTI was 10 −3 m −3 and the temperature of the main plasma changed from a few to tens of eV, depending on the discharge parameters [8,29]. Diagnostic ports are reserved in acceleration region for plasma performance and parameter measurements, such as electron density, electron temperature, discharge current, discharge voltage, impurity emission measurements, and so on.…”