High-voltage virtual-cathode microwave simulations
In contrast to a conventional microwave tube, a virtual-cathode device operates above the space-charge limit where the depth of the space-charge potential is sufficiently large to cause electron reflection. The region associated with electron reflection is referred to as a virtual cathode. Microwaves can be generated through oscillations in the position of the virtual cathode and by reflexing electrons trapped in the potential well formed between the real and virtual cathodes. A virtual-cathode device based on the first mechanism is a vircator while one based on latter mechanism is a reflex diode. A large number of low-voltage virtual-cathode microwave configurations have been investigated. Initial simulations of a high-voltage virtual-cathode device using a self-consistent particle-in-cell code indicated reasonable conversion efficiency with no frequency chirping. The nonchirping character of the high-voltage virtual-cathode device lead to the interesting possibility of locking four very-high-power microwave devices together using the four transmission lines available at Aurora. Subsequently, in support of two high-voltage experiments, simulations were used to investigate the effect of field-emission threshold and velvet position on the cathode; anode and cathode shape; anode-cathode gap spacing; output waveguide radius; diode voltage; a cathode-coaxial-cavity resonator; a high-frequency ac-voltage drive; anode foil scattering and energy loss; and ion emission on the microwave frequency and power. Microwave
- Research Organization:
- Los Alamos National Lab., NM (United States)
- Sponsoring Organization:
- DOE; DOD; USDOE, Washington, DC (United States); Department of Defense, Washington, DC (United States)
- DOE Contract Number:
- W-7405-ENG-36
- OSTI ID:
- 5196990
- Report Number(s):
- LA-UR-91-2834; CONF-9109279--1; ON: DE92000317
- Country of Publication:
- United States
- Language:
- English
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AMPLIFIERS
C CODES
CATHODES
COMPUTER CODES
COMPUTERIZED SIMULATION
DESIGN
ELECTRIC DISCHARGES
ELECTRODES
ELECTRON SOURCES
ELECTRONIC EQUIPMENT
EQUIPMENT
FREQUENCY RANGE
FUNCTION GENERATORS
HIGH-VOLTAGE PULSE GENERATORS
I CODES
MHZ RANGE
MHZ RANGE 100-1000
MICROWAVE AMPLIFIERS
MICROWAVE EQUIPMENT
PARTICLE SOURCES
PULSE GENERATORS
RADIATION SOURCES
RF SYSTEMS
SIMULATION
SPACE CHARGE
VOLTAGE DROP