Properties of the plasma channel in liquid discharges inferred from cathode local temperature measurements
- University of Geneva, Department of Condensed Matter Physics, 24 Quai E.-Ansermet, CH-1211 Geneva 4 (Switzerland)
The properties of the plasma channel at the cathode surface in a liquid discharge have been studied by means of temperature measurements and heat transfer numerical analysis. The studied discharge (current: 5 A; duration: 100 {mu}s; gap: 10 {mu}m) is typical of electrical discharge machining (EDM) in the semifinishing operation. The temperature information is obtained from two independent experiments: (1) microthermocouples patterned on the cathode, close to the discharge have been used to record the temperature variation caused by a single discharge with a high local resolution and large bandwidth; (2) the geometry of the resolidified layer, which gives the maximum extension of the melting point temperature isotherm, has been measured. These temperature data have then been compared to numerical simulation using inverse calculations allowing the experimental determination of two fundamental quantities of the discharge cathode interaction: (1) the power fraction transferred from the discharge to the sample, which was found to be close to 10% and (2) the exponent n of the power law expansion of the plasma channel r{sub plasma}{proportional_to}t{sup n}, which is n=0.2. The validity of the present analysis relies on the fact that the experimental temperature information is obtained for different values of the parameter r{sub plasma}/t{sub 0}{sup 2}, where t{sub 0}{sup 2} is the characteristic time of the experiment.
- OSTI ID:
- 20714142
- Journal Information:
- Journal of Applied Physics, Journal Name: Journal of Applied Physics Journal Issue: 11 Vol. 98; ISSN JAPIAU; ISSN 0021-8979
- Country of Publication:
- United States
- Language:
- English
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