Pellet injection research on the HT-6M and HT-7 tokamaks

Abstract

A multishot in situ pellet injection system has been constructed in the Institute of Plasma Physics. Single-and multi-pellet injection experiments were performed on the HT-6M and superconducting HT-7 tokamaks. The system proved to be convenient and reliable to operate. Pellets were fired into ohmically and LHCD and ICRF heated plasmas. Single pellet injection in ohmic discharge was found to increase the central density of HT-7 by about one half, while two pellet injection increased the central density in a step-like fashion by one half with each shot. Peaking of the electron density profile and a hollow electron temperature profile were obtained.

Predictions of Plasma Behavior Due to Pellet Injection for Future Thailand Tokamak

“…In the previous experiment of HT-6M [22], the machine was equipped with the pellet injector system. It was designed to produce hydrogen pellets in a cylindrical shape with 0.6 -0.8 mm in diameter, and 0.8 mm in length.…”

“…We first performed simulations of the pellet injec-tion based on the previous design and compare with the previous experimental results [22]. Based on their design, the cylindrical pellet of size 0.6 mm diameter and 0.8 mm length is equivalent to a spherical of radius size 3.78 × 10 −4 m. A single hydrogen pellet is launched from the LFS into the HT-6M plasma with two injection speeds of 100 m/s (low speed) and 600 m/s (high speed).…”

Study of confinement improvement in presence of a MARFE in the HT-7 superconducting tokamak

“…The major research fields on the HT-7 are steady-state operation, high-performance such as advanced tokamak operation modes, the fuelling study [27] and MARFE phenomena [28], lower hybrid wave (LHW) current drive [29] and ICRF heating [30]. For recent experiments on the HT-7, the following main diagnostics signals are effectively used in this paper as shown in Fig.…”

Study of the operational region with new graphite limiters in the Hefei tokamak-7

“…The major research fields on the HT-7 are steady-state operation, high performance such as advanced tokamak operation modes, a fuelling study [15], multifaceted asymmetric radiation phenomena from the edge [16], lower hybrid wave current drive (LHCD) [17] and ICRF heating [18]. For recent experiments on the HT-7, the following main diagnostics signals are effectively used in this paper: a 16-channel extreme ultraviolet bolometer array to measure plasma radiation losses, a seven-channel bremsstrahlung emission to measure Z eff , a multichannel H α (D α ) radiation array, ten-channel C III line emission, an impurity optical spectrum measurement system and the electron density profile measured by a vertical five-channel farinfrared (FIR) hydrogen cyanide (HCN) laser interferometer [19,20].…”