The purpose of this paper is to understand the behavior of GHTAW process under the space
environment with the experimental and numerical analysis. Gas Hollow Tungsten Arc Welding (GHTAW)
using a hollow tungsten electrode was adopted, since the ignition and discharge of a conventional GTAW
process is not appropriate to the space environment due to low pressure in space. In order to clarify the
phenomena of GHTAW under space environment, an investigation of thermal and physical properties of the
GHTAW arc plasma was experimentally performed under low pressure conditions. Furthermore, the molten
pool behavior and weldment of GHTAW were understood by CFD-based numerical analysis, based on the
models of GHTA heat source, arc pressure and electromagnetic force induced by arc plasma, the
characteristics of which were obtained by the captured images of a CCD camera.