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Title: Long-pulse, high-power vircator experiments

Conference ·
OSTI ID:7158593

An experiment designed to achieve long pulse virtual cathode oscillator (VCO) operation at approx. 700 MHz is described. Low frequency operation allowed operating at large A-K gaps and low current densities which facilitated the 800 ns pulsewidth operation. The VCO was configured in a 91 cm diameter drift tube and consisted of a 76 cm diameter planar cathode separated from an anode screen by an A-K gap that was varied from 5 to 10 cm. The diode was directly driven by a Marx generator with a resultant A-K voltage of 350 kV. Power was extracted axially from the cylindrical waveguide through a Lexan window. Application of a transverse magnetic field downstream of the virtual cathode swept the beam into the wall. This method of dumping the beam avoided plasma formation at the window and a resultant shortening of the radiated pulse. The frequency was observed to chirp from 600 to 800 MHz. The radiation pattern was measured by a seven element B-dot array located 2.4 m from the exit window. Comparison of these patterns to computer code predictions indicated a mix of TM/sub 0/exclamation and TM/sub 02/ modes.

Research Organization:
Sandia National Labs., Albuquerque, NM (USA)
DOE Contract Number:
AC04-76DP00789
OSTI ID:
7158593
Report Number(s):
SAND-87-3007C; CONF-8805132-6; ON: DE88011787
Resource Relation:
Conference: 4. national high power microwave conference, Monterey, CA, USA, 9 May 1988; Other Information: Portions are illegible in microfiche products
Country of Publication:
United States
Language:
English