Measurement of velocity and diameter of tungsten particles produced by arcing using high-speed video

Abstract

Arcing is a mechanism of dust production and erosion in fusion devices. The masses and velocities of tungsten (W) particles produced by arcing is of special interest given that W is used as wall material in current experimental devices and is planned for use in new machines such as ITER. This work presents a new technique for evaluation of the parameters of particles produced by vacuum arcs in laboratory conditions based on direct observation with a high-speed video camera. Tracking of particle trajectory provides a measurement of velocity and angle of emission. Additionally, the emitted thermal radiation of the particles is measured and its evolution over time is compared with a model of its cooling in order to obtain a measurement of size and temperature at the moment of emission for each individual particle. Surprisingly, temperature measurements reveal the production of initially solid particles. The newly established video technique allows automated measurement of a high number of particles in order to obtain distributions of the particle parameters.

Keywords

• Arcing
• Dust production
• Tungsten
• Plasma-facing components
• Droplets
• Vacuum arcs