Thermal research of a single crystal tungsten target positron source for the STCF project in China

Abstract

A new generation electron–positron collider, the Super Tau-Charm Facility (STCF), has been proposed in China. As a critical part of the STCF Linac, the positron source will use a 10 nC/50 Hz 1.5 GeV electron beam to bombard a single crystal tungsten target. To obtain a stable and reliable positron source with a long lifetime, this paper presents a molecular dynamics model to simulate the anisotropy of thermal conduction for single crystal tungsten. A series of electron beam bombardment experiments were performed, which confirmed that the anisotropy of thermal conductivity and the highest thermal conductivity for single-crystal tungsten is the close-packed crystallographic orientation of [111]. Scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD) were used to study the recrystallization of the single crystal tungsten target. Finally, a new oscillation motional target system was designed for the STCF, and thermal simulation and moving speed optimization were performed.