First results from solid state neutral particle analyzer on experimental advanced superconducting tokamak

Abstract

Full function integrated, compact solid state neutral particle analyzers (ssNPA) based on absolute extreme ultraviolet silicon photodiode have been successfully implemented on the experimental advanced superconducting tokamak to measure energetic particle. The ssNPA system has been operated in advanced current mode with fast temporal and spatial resolution capabilities, with both active and passive charge exchange measurements. It is found that the ssNPA flux signals are increased substantially with neutral beam injection (NBI). The horizontal active array responds to modulated NBI beam promptly, while weaker change is presented on passive array. Compared to near-perpendicular beam, near-tangential beam brings more passive ssNPA flux and a broader profile, while no clear difference is observed on active ssNPA flux and its profile. Significantly enhanced intensities on some ssNPA channels have been observed during ion cyclotron resonant heating.

A simulation study of a windowless gas stripping room in an E//B neutral particle analyzer

“…It is filled in the stripping room from the top flange (5) of the vacuum chamber through a bellow (4). A machinery bearing molecular pump with a pumping speed of 340 L/s is used at the bottom of vacuum chamber together with a gate valve (11) in this work. The pressure distribution inside the stripping chamber is one of the main concerns of our design.…”

“…A pressure type gas inlet is defined at the top flange (5) of vacuum chamber and the pressure at the gas inlet P 0 ranges from 20 to 400 Pa with step of 20 Pa set in the simulation. Three pressure type gas outlets are defined at the entrance, exit holes (7 and 8) and the bottom of gate valve (11). A pressure of 10 −3 Pa is assumed for all three outlets.…”

“…This results in the pumping speed of 12.4 L/s through the entrance and exit holes. A pumping speed of 340 L/s is set at the bottom of the gate valve (11).…”

“…It is used to determine the bulk ion temperature, the isotopic ratio and the fast ion distribution of the plasma, by measuring the charge exchange neutral particles escaping from the plasma. Different types of NPA have been built in Tokamak facilities worldwide [2][3][4][5][6][7][8][9][10][11][12][13], such as the parallel direction of electric and magnetic fields (E//B) NPA on the Tokamak Fusion Test Reactor (TFTR) [2], the compact neutral particle analyzer (CNPA) on the Wendelstein 7-AS stellarator [3], the low-and high-energy neutral particle analyzers (LENPA and HENPA) on the International Thermonuclear Experimental Reactor (ITER) [10], the solid state NPA (ss-NPA) on the Experimental Advanced Superconducting Tokamak (EAST) [11] and the CP-NPA on the HuanLiuqi-2A (HL-2A) [12].…”

“…Stripping unit plays an important role in the analyzing of the neutral particles, except for the flux measurement NPA such as ssNPA [11]. It provides a place to reionize the charge exchange neutral particles.…”