Characteristics of a plasma electron beam generated by using a tantalum hollow cathode in low pressure argon atmosphere are described.
Results of the experiment are summarized in the followings.
1. With constant flow rate of argon quite stable current vs. voltage characteristic was obtained.
2. The temperature of the tantalum hollow cathode measured by an optical-pyrometer through observation window was around 2400°K.
3. With the cathode-to-anode distance 50mm, a maximum power density of approximately 3 kw/cm
2 was obtained without focusing magnetic field. With very long cathode-to-anode distance the power density between several tens of watt/cm
2 could be obtained.
4. With cathode-to-anode distance of less than 80mm, thermal efficiency of more than 80 percent was obtained. More than 50 percent of the total heat loss was caused by radiation from the cathode surface.
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