Realization of a Stable and Highly Efficient Gyrotron for Controlled Fusion Research

The operating characteristics of a 140 GHz, pulsed gyrotron are reported. Total efficiencies of 36% and ouput powers of 175 kW have been obtained in single mode operation.Measurements of power and efficiency have been made for a variety of modes between 120 and 160 GHz, and these results are in good agreement with predictions based on nonlinear theory. The best results have been obtained with isolated, asymmetric modes, such as the TE 4 , 2 , 1 (127.3 GHz), TE 2 , 3 , 1 (136.7 GHz),and the TE 3 , 3 , 1 (155.6 GHz). Although mode competition was found to prevent the TEO, 3 , 1 mode (139.5 GHz) from reaching the optimum operating conditions, an output power of 138 kW and total efficiency of 29% were achieved with this mode. A variety of new, highly accurate diagnostic techniques that have been developed to measure the power, frequency, and mode content of the output radiation will be reviewed. In addition, the operating characteristics of both laminar and nonlaminar magnetron injection guns will be compared. The high powers and efficiencies obtained in this experiment are promising for the extension of gyrotron output powers to the megawatt range.2

Section: Introductionmentioning

confidence: 99%

High efficiency operation of a 140 GHz pulsed gyrotron

Kreischer

Schutkeker

Danly

et al. 1984

“…Previous analysis (Ganguly and Chu 1981) has shown that efficiencies greater than 50% are available using constant magnetic fields. These calculations and the experiment with a complex-cavity gyrotron (Carmel et al 1983) have shown efficiency enhancement by tapering the magnetic field. A program for GKA exploratory development, which includes both experiment and theory, is under way.…”

Section: G Yrotron Researchmentioning

confidence: 94%

Gyrotron and ubitron amplifier research at the Naval Research Laboratory

Freund¹,

Ganguly²,

Parker³

et al. 1984

Self Cite

“…However, predictions of high-power gyro-klystron performance can be made by employing existing numerical codes which describe the linear and non-linear behaviour of gyro-klystrons (Ganguly and Chu 1981). Considerable confidence may be attached to the predictions of these codes, since they were used to successfully design and predict performance of complex-resonator gyrotrons (Carmel et al 1983).…”

Section: Prospects For Developing High Pulsed Power Gyro-klystron Ampmentioning

confidence: 99%

“…demonstration of enhanced mode stability was achieved at 35 GHz using TEo I/TE o4 coupled cavities; output power was 340 kW in I-liS pulses and efficiency was beller than 50% (Carmel et al 1983). The application of this complex-cavity concept to the development of high CW power gyrotrons will be discussed in the next section.…”

Section: Introductionmentioning

confidence: 98%

High average power and high peak power gyrotrons: present capabilities and future prospects†

Granatstein

1984

We survey work in the U.S.A. High average power gyrotrons (1 MW at 100-150GHz) are required for ECRH of magnetic fusion plasmas. Even though gyrotrons have superior mode stability compared with other tubes, they must be so grossly overmoded to handle 1 MW CW that mode control does become an issue. Studies of gyrotron-oscillator cavity designs with enhanced mode stability properties are described, including complex and Fabry-Perot cavities. In the complex cavity concept, two cavities each operating in a different mode are strongly coupled. Exploitation of this concept in a 60 G Hz TED I/TE 0 1 gyrotron has already resulted in power greater than 200kW CWo Designs of TE 0 3jTE 0 4 and TE 0 3/TE 0 6 gyrotrons which promise to extend performance are discussed. A 115GHz gyrotron using a Fabry-Perot cavity has been successfully demonstrated at power levels above 50 kW and prospects of extending performance are considered. Study of high peak power gyrotrons is stimulated by the perceived requirement for 300 MW RF sources at i. -3 cm to drive very high energy (I TeV) linear electron accelerators. For this application, the phase of the microwave signal must be precisely controllable. These demanding requirements have led to renewed interest in gyro-klystron amplifiers, and studies of relatively low power gyro-klystrons will be reviewed. Finally, a design of a 300 MW gyro-klystron is presented.