Self-excitation of spurious oscillations in the drift region of gyrotrons and their influence on gyrotron operation

Antakov, I. I.; Gachev, I. G.; Zasypkin, E. V.

doi:10.1109/27.338303

Cited by 28 publications

(12 citation statements)

References 3 publications

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“…A notable effort has been devoted to the theoretical and experimental study of these oscillations. Based on these studies [1,2,3,4], essentially three different strategies for suppressing spurious instabilities in gyrotron beam ducts have been studied and implemented. The first one is to use a smooth-wall dielectric loaded beam duct, made from SiC [2].…”

Section: Introductionmentioning

confidence: 99%

“…The first one is to use a smooth-wall dielectric loaded beam duct, made from SiC [2]. The second is the use of a metallic beam duct with a random surface [1,5]. The third one is the stacked ring beam duct, composed by rings of copper and dielectric material, like BeOSiC [4,6].…”

Section: Introductionmentioning

confidence: 99%

“…A distinction can be made between the models treating the beam-wave interaction self-consistently or not. Among the non-self consistent models, some are assuming a fixed field profile [1]. They compute the electric field profile for a given geometry and evaluate afterwards its effect on the interaction [7].…”

Section: Introductionmentioning

confidence: 99%

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Parasitic Oscillations in Smooth-Wall Circular Symmetric Gyrotron Beam Ducts

Genoud

Alberti

Tran

et al. 2018

J Infrared Milli Terahz Waves

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In order to study parasitic oscillation that may occur in a realistic beam duct upstream to the gyrotron cavity, the self-consistent linear and spectral code TWANGlinspec has been modified. The large inhomogeneities in the smooth-wall beam duct geometry or in the magnetic field profile required the implementation of a numerical approach using a hybrid finite element method. The new model permits to characterize a large number of potentially spurious TE modes. Compared to previous studies on gyrotron beam duct instabilities, an extended interaction space including also the gyrotron cavity has been considered. The role of the connecting part between the beam duct and the cavity, called spacer, is highlighted and it is shown that the gyro backward-wave TE modes excited in this region generally have their minimum starting current. The sensitivity of the minimum starting current on electron beam velocity spread is also evaluated.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Parasitic Oscillations in Smooth-Wall Circular Symmetric Gyrotron Beam Ducts

Genoud

Alberti

Tran

et al. 2018

J Infrared Milli Terahz Waves

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“…An increase in the high-frequency field in a gyrotron cavity can be described from the viewpoint of the development of the instability which is sometimes called an MCR instability (see, e.g., [7][8][9]). At the same time, it can also develop in the HEB formation region, if some part of the electron drift channel acts as a cavity [1,10]. In the absence of metal electrodes encompassing the helical electron beam, an electrostatic cyclotron instability (negative-mass instability), which has the convective character, can develop in it (see, e.g., [9,[11][12][13]).…”

Section: Introductionmentioning

confidence: 99%

“…Frequently, spurious radiation in various spectrum regions, which is indicative of the presence of such fields, accompanies the operation of high-power gyrotrons and prevents achievement of calculated values of the output parameters of the tubes. In the case of high radiation intensity it can even cause deterioration of the tube elements and failure of measuring tools (e.g., see [1][2][3][4][5][6]). Appearance of high-frequency fields can be caused by various instabilities, which can develop in the electron beam due to spurious resonance cavities in the device or to external circuits.…”

Section: Introductionmentioning

confidence: 99%

Simulation of low-frequency collective processes in gyrotron electron beams

Luksha

2009

Radiophys Quantum El

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UDC 621.385We simulate collective processes in an electron space charge trapped between the cathode and the magnetic mirror in gyrotron-type systems using the particle-in-cell method. Threshold conditions of excitation and frequency-amplitude characteristics of low-frequency oscillations connected with the development of an instability in a space charge in the trap are determined using a gyrotron with an output power of 100 kW and a radiation wavelength of 4 mm as an example. The mechanism of the instability development in an ensemble of anharmonic electron oscillators is proposed and used to analyze the method of oscillation suppression based on varying the magnetic-field distribution in the region of the beam compression. The influence of low-frequency oscillations on the parameters of the electron beam entering the cavity is studied. The obtained calculation data are compared with the results of the experiments studying the parameters of low-frequency collective processes in gyrotrons.

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