Generation of trains of ultrashort microwave pulses by two coupled helical gyro-TWTs operating in regimes of amplification and nonlinear absorption

Abstract

Based on a time-domain model, we demonstrate that a periodic train of powerful ultrashort microwave pulses can be generated in an electron oscillator consisting of two coupled helically corrugated gyrotron travelling wave tubes (gyro-TWTs) operating in regimes of amplification and saturable absorption, respectively. The mechanism of pulse formation in such an oscillator is based on the effect of passive mode-locking widely used in laser physics. Saturable absorption can be implemented in a gyro-TWT in the Kompfner dip regime by a proper matching of the guiding magnetic field. According to simulations with the parameters of an experimentally realized Ka-band gyro-TWT, the peak power of generated pulses with a duration of 200 ps can achieve 400 kW.

Development of gyrotron traveling-wave tubes at IAP and GYCOM

“…2) [9]; various microwave systems for inputting and outputting the radiation to and from a tube through one window [7,8,10]; tubes operating at the third cyclotron harmonic [11]; tubes prospective for DNP-NMR spectroscopy (260 GHz) [12]; tubes generating periodical sequences of ultrashort phasecoherent pulses [13].…”

Self-generation of chaotic dissipative multisoliton complexes supported by competing nonlinear spin-wave interactions

“…The spiral-type TWT operates as a signal suppressor in the Kompfner deep mode [27]. In this mode, a gyro-TWTsuppressor was used as a fast saturable absorber in a gyro-TWT generator model for passive mode-locking and self-generation of ultrashort pulses [28]. It is necessary to note that in a microwave region, a MSW signal-to-noise enhancer also has responses corresponding to a saturable absorber [29].…”

PIC Simulations of Ka-band Ultra-Short Pulse Oscillator with Resonance Cyclotron Absorber in the Feedback Loop

“…In [1,2] it was shown that periodical trains of ultrashort microwave pulses (USP) can be produced in a two-section microwave oscillator consisting of an amplifier and a nonlinear (saturable) absorber in the feedback loop. In such a system, the process of pulse formation is based on the effect of passive modelocking which is well known in laser physics [3].…”

“…2 one. The gyro-TWT was fed by an encircling electron beams with the following parameters: electron energies of 70 keV, beam current of 6...10 A, pitch factor 1 ... 1.3, magnetic field of 0.68..0.7 T. Parameters of corrugation were chosen in such a way as to provide an optimum amplification of ultrashort pulses [2].…”