Optical Investigation of Plasma Formation Process by Interaction of Intense Electron Beams with Metallic Targets
W. Ana, V. Engelkob, G. Muellera and A. Weisenburgera
a Forschungszentrum Karlsruhe GmbH, IHM, P.O. Box 3640, 76021 Karlsruhe, Germany,
b Efremov Institute of Electrophysical Apparatus, 196641, St. Petersburg, Russia
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Electron beams with energies ≥ 100 keV offer attractive possibilities to modify metallic surfaces. Numerous experiments with the electron accelerators GESA I and II showed excellent results regarding the improvement of mechanical properties and the enhancement of the corrosion resistance of the treated materials. The next step leads to further technological adaptation of the process that especially was focused on the adaptation of the electron beam to the surface geometry. For the treatment of the outer surface of tubes the electron beam facility GESA IV with a radial converged electron beam was designed. In first experiments unexpected electrical short circuiting after different time periods occurred. Two major reasons could be identified: excessive plasma formation at the cathode and target plasma formation. The latter can be controlled by vacuum conditions and surface cleaning of the target, the first by controlling the duration of plasma formation at the cathode.
DOI: 10.12693/APhysPolA.115.1183
PACS numbers: 07.68.+m, 29.25.Bx, 41.75.Ak