Experimental Verification of Frequency Multiplication in Two-stage Tapered Gyro-TWT

C. W. Baik, S. G. Jeon, D. H. Kim, A. K. Sinha, Nobuyuki Sato, K. Yokoo, G. S. Park

Research output: Contribution to journalConference article

1 Citation (Scopus)

Abstract

A Ka-band harmonic multiplying two-stage tapered gyro-TWT has been developed. The third harmonic interaction of electron cyclotron frequencies is used to multiply X-band signals to Ka-band. A previous similar experimental demonstration at NRL showed a 20 % bandwidth at saturated gain of 25 dB with 16 % efficiency when the predicted velocity spreads of 4 % were assumed at Ka-band with the fundamental harmonic interaction. This work showed the linearly taperpd rectangular waveguide at both stages could produce enhanced gain, gain uniformity, and efficiency. Here, for a harmonic multiplying gyro-TWT, a self-consistent large-signal calculation predicts a saturated gain of 23.8 dB, an electronic efficiency of 12 %, and a bandwidth of 4.1 % on the assumption of 4 % axial velocity spread of the electron beam when an axis-encircling electron beam at a moderate beam voltage of 30 kV and a current of 1 A is employed. For a proof-of-principle, experimental setup is prepared. An electromagnet up to 5 kG and 13 sub-magnets to control the tapered magnetic field are constructed and tested. An axis-encircling electron gun with a single cusp is operated at the beam voltage of 30 kV and the beam current of 1 A. Interaction circuits are fabricated and tested. A 0-dB directional coupler shows a good performance as HFSS predicts. For the first time, triple frequency multiplication from 11.4GHz to 34.2GHz has been experimentally verified in the high power Ka-band gyrotron traveling-wave tube amplifier. Hot test for optimum output power is presently underway. Both experimental and theoretical works including a Particle-In-Cell Code MAGIC3D on this device will be presented in details. The separate abstract on the velocity spreads measurement is also submitted.

Original languageEnglish
Number of pages1
JournalIEEE International Conference on Plasma Science
Publication statusPublished - 2003 Oct 17
Event2003 IEEE International Conference on Plasma Science - Jeju, Korea, Republic of
Duration: 2003 Jun 22003 Jun 5

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics
  • Condensed Matter Physics
  • Electrical and Electronic Engineering

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