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Title: Investigation of a 140 GHz gryo-backward wave oscillator and a 95 GHz gyro-traveling wave

Abstract

There is current interest in developing a high-power source of continuously tunable millimeter wave radiation as a RF driver for high-power gyrotron, CARM, or FEL amplifiers. The gyrotron backward wave oscillator is a voltage-tunable fast-wave device that can satisfy these requirements. This thesis reports on the design and experimental investigation of a 130--145 GHz gyrotron backward wave oscillator Novel operating features of this design include the use of a 80-kV, 6.2-A Pierce-wiggler electron beam source, a broadband motheye window and an overmoded TE{sub 1,2} cylindrical interaction waveguide. Although this device has demonstrated voltage-tunable operation over the design range in the TE{sub 1,2} mode, the frequency tuning is not continuous, output powers were low and full-beam transmission through the interaction region was not possible. Simulations indicate that the beam has very high velocity spread induced by space charge forces in the compression region. After increasing the diameter of the beam tunnel to achieve full transmission, the TE{sub 1,2} was not found. It is felt that the scraping off of the beam edge in the initial experiments allowed a better quality beam to enter the interaction region and inhibited coupling into competing forward wave modes. The need for radar systems with greatermore » resolution has led to renewed interest in the development of efficient high-power amplifiers at 95 GHz. Current sources are limited to 6--8 kW of output power due to ohmic loading on the slow-wave circuit. A gyrotron traveling wave tube amplifier is capable of efficient operation over a wide bandwidth with the added attraction of low ohmic loading on the smooth fast-wave circuit. This thesis reports of the design a 95-GHz gyrotron traveling wave tube amplifier that is capable of high power (125 kW), high gain (38 dB), large bandwidth > 5 GHz and high efficiencies (> 30%).« less

Authors:
 [1]
  1. Massachusetts Inst. of Tech., Cambridge, MA (United States)
Publication Date:
Research Org.:
Oak Ridge Inst. for Science and Education, TN (United States); Massachusetts Inst. of Tech., Cambridge, MA (United States)
Sponsoring Org.:
USDOE, Washington, DC (United States); Department of Defense, Washington, DC (United States)
OSTI Identifier:
10187901
Report Number(s):
DOE/OR/00033-T534
ON: DE94000828; TRN: 93:025449
DOE Contract Number:  
AC05-76OR00033
Resource Type:
Thesis/Dissertation
Resource Relation:
Other Information: DN: Thesis submitted to Massachusetts Institute of Technology, Cambridge, MA.; TH: Thesis (M.S.); PBD: 1 Sep 1992
Country of Publication:
United States
Language:
English
Subject:
42 ENGINEERING; OSCILLATORS; DESIGN; MICROWAVE AMPLIFIERS; TRAVELLING WAVE TUBES; GHZ RANGE 01-100; GHZ RANGE 100-1000; PERFORMANCE; OSCILLATION MODES; ELECTRON BEAMS; EFFICIENCY; 426000; COMPONENTS, ELECTRON DEVICES AND CIRCUITS

Citation Formats

Basten, M A. Investigation of a 140 GHz gryo-backward wave oscillator and a 95 GHz gyro-traveling wave. United States: N. p., 1992. Web.
Basten, M A. Investigation of a 140 GHz gryo-backward wave oscillator and a 95 GHz gyro-traveling wave. United States.
Basten, M A. Tue . "Investigation of a 140 GHz gryo-backward wave oscillator and a 95 GHz gyro-traveling wave". United States.
@article{osti_10187901,
title = {Investigation of a 140 GHz gryo-backward wave oscillator and a 95 GHz gyro-traveling wave},
author = {Basten, M A},
abstractNote = {There is current interest in developing a high-power source of continuously tunable millimeter wave radiation as a RF driver for high-power gyrotron, CARM, or FEL amplifiers. The gyrotron backward wave oscillator is a voltage-tunable fast-wave device that can satisfy these requirements. This thesis reports on the design and experimental investigation of a 130--145 GHz gyrotron backward wave oscillator Novel operating features of this design include the use of a 80-kV, 6.2-A Pierce-wiggler electron beam source, a broadband motheye window and an overmoded TE{sub 1,2} cylindrical interaction waveguide. Although this device has demonstrated voltage-tunable operation over the design range in the TE{sub 1,2} mode, the frequency tuning is not continuous, output powers were low and full-beam transmission through the interaction region was not possible. Simulations indicate that the beam has very high velocity spread induced by space charge forces in the compression region. After increasing the diameter of the beam tunnel to achieve full transmission, the TE{sub 1,2} was not found. It is felt that the scraping off of the beam edge in the initial experiments allowed a better quality beam to enter the interaction region and inhibited coupling into competing forward wave modes. The need for radar systems with greater resolution has led to renewed interest in the development of efficient high-power amplifiers at 95 GHz. Current sources are limited to 6--8 kW of output power due to ohmic loading on the slow-wave circuit. A gyrotron traveling wave tube amplifier is capable of efficient operation over a wide bandwidth with the added attraction of low ohmic loading on the smooth fast-wave circuit. This thesis reports of the design a 95-GHz gyrotron traveling wave tube amplifier that is capable of high power (125 kW), high gain (38 dB), large bandwidth > 5 GHz and high efficiencies (> 30%).},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {1992},
month = {9}
}

Thesis/Dissertation:
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