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Study of an eighth-harmonic large-orbit gyrotron in the terahertz band

Research output: Contribution to Journal/MagazineJournal articlepeer-review

  • Xiang Li
  • Jiandong Lang
  • Yasir Alfadhl
  • Xiaodong Chen
<mark>Journal publication date</mark>02/2015
<mark>Journal</mark>IEEE Transactions on Plasma Science
Issue number2
Number of pages9
Pages (from-to)506-514
Publication StatusPublished
Early online date7/01/15
<mark>Original language</mark>English


A 0.42-THz eighth-harmonic large-orbit gyrotron (LOG) operating with TE8,1,1 mode has been designed and studied. The LOG design is characterized by the requirement of low external magnetic field and short cavity length to limit the ohmic loss. The cold cavity analysis is presented and followed by the hot cavity simulation with the 3-D particle-in-cell code. It is shown in the initial hot test that by proper choice of the electron beam source, the eighth harmonic of the electron cyclotron resonance can be selectively excited at 0.42 THz with an output power of 3.8 kW, which requires an external magnetic field as low as 2.8 T. Based on the model, the starting oscillation process of TE8,1,1 mode at the eighth harmonic and the dynamic of beam-wave interaction are investigated. Upon verification of the design and modeling, a number of parameter variation studies are conducted to draw broader conclusions about the beam-wave interaction behavior in a high-harmonic LOG. The design procedure and the conclusion of this paper can be generalized and applied to other LOGs.