Pulsed testing of a quasioptical gyrotron for materials processing

Conference · Thu Jul 01 04:00:00 EDT 1999

OSTI ID:20034291

Fischer, R P; Fliflet, A W

The quasioptical gyrotron (QOG) is under development at the Naval Research Laboratory as a high power source of millimeter-wave radiation. Recent experimental results include the production of up to 150 kW output power with 205 efficiency in 13 {micro}sec pulses. A new application of the QOG is the processing of ceramics and other non-metallic materials. High power millimeter-wave radiation offers unique capabilities for the application of coatings, sintering, brazing and soldering, and treatment of polymers. The new experiment is designed to produce 4 kW average power from 75--95 GHz using a 20 kV, 1.5 A dc electron beam. Initial pulsed testing has been performed at 20--60 kV cathode voltage, 0--6 A in 13 {micro}sec pulses. A pair of capacitive probes in the drift region are used to measure the average pitch ratio ({alpha} = {nu}{sub {perpendicular}}/{nu}{sub {parallel}}) of the gyrating electron beam. The pitch ratio is varied by adjusting the magnetic field at the gun or the intermediate anode voltage. Measurements indicate that the average {alpha} of the beam is less than simulation values for low cathode voltages. However, increasing the cathode voltage to 55 kV greatly improves the beam quality. Initial efficiencies in the untitled resonator are unexpectedly low ({eta} = 5%), as is the maximum frequency detuning ({Delta}{omega}/{omega} = 2%). Tilting the resonator by 2{degree} relative to the plane perpendicular to the electron beam is predicted to increase the achievable frequency detuning and single-mode output efficiency. An asymmetric tilted resonator has been installed in the gyrotron and cold tested at 94 GHz. Pulsed measurements will be performed on gyrotron output power, efficiency, mode spectrum, and output radiation pattern. This tunable QOG will complement existing processing experiments at 2.45, 35, and 83 GHz.

• Research Organization: Naval Research Lab., Washington, DC (US)
• Sponsoring Organization: Office of Naval Research
• OSTI ID: 20034291
• Country of Publication: United States
• Language: English

Related Subjects

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION
36 MATERIALS SCIENCE
CERAMICS
ENERGY EFFICIENCY
GHZ RANGE 01-100
MANUFACTURING
MICROWAVE AMPLIFIERS
POLYMERS
USES