Diameters and Velocities of Droplets Emitted from the Cu Cathode of a Vacuum Arc

Cathode spots of vacuum arcs emit cathode material in the form of plasma as well as droplets. Generated by arcs burning at the first wall of fusion devices the droplets may effectively contaminate the fusion plasma. Essential characteristics of the droplets (diameter, velocity, and emission directio...

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Bibliographic Details
Published in2018 28th International Symposium on Discharges and Electrical Insulation in Vacuum (ISDEIV) Vol. 1; pp. 325 - 328
Main Authors Siemroth, Peter, Laux, Michael, Pursch, Heinz, Sachtleben, Jurgen, Balden, Martin, Rohde, Volker, Neu, Rudolf
Format Conference Proceeding
LanguageEnglish
Published IEEE 01.09.2018
Subjects
Atmospheric measurements
Cathodes
Discharges (electric)
droplet velocities
Electron tubes
light scattering
Particle measurements
Plasmas
vacuum arc
Vacuum arcs
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Summary:Cathode spots of vacuum arcs emit cathode material in the form of plasma as well as droplets. Generated by arcs burning at the first wall of fusion devices the droplets may effectively contaminate the fusion plasma. Essential characteristics of the droplets (diameter, velocity, and emission direction) and their interrelations are poorly known so far. In the present paper, a new approach of optical droplet investigation is presented. Generated by a pulsed vacuum arc, the droplets fly vertically inside a drift tube against gravity finally passing a light beam. The time-of-flight and the detected scattered light allow a simultaneous determination of droplet velocity and size. Different solid angle directions have been realized by rotating the cathode with respect to the flight tube axis. Using this technique the sizes and velocities of droplets emitted from a Cu cathode into different directions were obtained.
ISSN:2471-786X
DOI:10.1109/DEIV.2018.8537044