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Diagnostics of DC plasma jets generated with Laval anodes

Book ·
OSTI ID:377753
; ;  [1];  [2]
  1. Univ. de Sherbrooke, Quebec (Canada)
  2. DLR-Institute for Technical Thermodynamics, Stuttgart (Germany)
Plasma jets originating from d.c. torches equipped with Laval nozzles are considered to be more efficient for both vacuum and atmospheric plasma spraying than those generated with the standard cylindrical anodes. The present study is devoted to the measurement of the temperature and velocity fields in plasma jets resulting from three different nozzles: a cylindrical and two Laval anodes with nominal Mach numbers of 2.5 and 3. The enthalpy probe and emission spectroscopy techniques are used for this purpose. Attention is given to the effect of the chamber pressure on the distribution of the temperature and velocity fields. The results show that when Laval nozzles are used at reduced chamber pressure (200 torr), the jets are wider, with higher temperature and velocity values in the central regions, compared to those obtained using cylindrical anodes. These characteristics are expected to improve the results of plasma spraying processes with respect to the layer quality and deposition efficiency.
OSTI ID:
377753
Report Number(s):
CONF-9509182--; ISBN 0-87170-541-9
Country of Publication:
United States
Language:
English