Design Considerations for Powerful Continuous-Wave Second-Cyclotron-Harmonic Coaxial-Cavity Gyrotrons

Avramides, K.A.; Iatrou, C.T.; Vomvoridis, J. L.

doi:10.1109/tps.2004.828781

Cited by 36 publications

(36 citation statements)

References 13 publications

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“…It can be achieved by the proper choice of the depth of grooves. However, this method can hardly be used to improve the ITER relevant coaxial gyrotrons, since the depth of the grooves should be kept inside the interval 0.2 < d/λ c < 0.25, where λ c is the cutoff wavelength of the operational mode, to avoid self-excitation on the higher cyclotron harmonics [3,5].…”

Section: Resultsmentioning

confidence: 99%

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Electromagnetic Analysis of Coaxial Gyrotron Cavity With the Inner Conductor Having Corrugations of an Arbitrary Shape

Zaginaylov¹,

Mitina²

2011

PIER B

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Abstract-The mathematical approach for the calculation of the membrane functions of a coaxial gyrotron cavity with an arbitrary corrugated inner rod is proposed. It is utilized mainly for two aims. First, it is shown that for typical parameters of the coaxial gyrotron cavity with the corrugated inner conductor the shape of corrugations only slightly influences the eigenvalues of competing eigen-modes. However, it can significantly influence the density of ohmic losses in the inner conductor. In particular, it is shown that the density of ohmic losses can be reduced almost twice by the proper choice of the corrugation shape. Second, it is shown that the usual idealizations of the corrugated surface of the inner conductor (the surface with rectangular grooves, having rounded edges, is approximated by a surface with wedged groves that have sharp edges) are correct. The physical interpretation of the obtained results and their practical meaning are discussed.

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Section: Resultsmentioning

confidence: 99%

“…The basic model for the electromagnetic analysis of a coaxial gyrotron cavity is the surface impedance model (SIM) [3][4][5] which is used in several codes [6] for simulation of a coaxial gyrotron operation. It is rather simple and convenient for use in different simulation tools.…”

Section: Introductionmentioning

confidence: 99%

Electromagnetic Analysis of Coaxial Gyrotron Cavity With the Inner Conductor Having Corrugations of an Arbitrary Shape

Zaginaylov¹,

Mitina²

2011

PIER B

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“…The cavity contour is very similar to the one of the gyrotron cavity having a cut-off section at one side and an up-taper at the other side, thus forming an open resonator. As in coaxial-cavity gyrotrons, a metallic insert is used to assist the easier excitation of the desired mode [7,8]. The outer wall of the cavity is perforated in the midsection area [9], so that the wave beam can couple to the resonant mode in the cavity.…”

Section: Advanced Measurement Setupmentioning

confidence: 99%

Computer-Controlled Test System for the Excitation of Very High-Order Modes in Highly Oversized Waveguides

Ruess

Avramidis

Gantenbein

et al. 2019

J Infrared Milli Terahz Waves

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The generation of a specific high order mode with excellent mode purity in a highly oversized cylindrical waveguide is mandatorily required for the verification of high power components at sub-THz frequencies. An example is the verification of quasi-optical mode conversion and output systems for fusion gyrotrons. A rotating high order mode can be excited by taking a low power RF source (e.g. RF network analyser) and by injecting the RF power via a horn antenna into a specific adjustable quasi-optical setup, the so-called mode generator. The manual adjustment of the mode generator is typically very time consuming. An automatized adjustment using intelligent algorithms can solve this problem. In the present work the intelligent algorithms consist of five different mode evaluation techniques to determine the azimuthal and radial mode indices, the quality factor, the scalar mode content and the amount of the counter-rotating mode. Here, the implemented algorithms, the design of the computer-controlled mechanical adjustment and test results are presented. The new system is benchmarked using an existing TE28,8 mode cavity operating at 140 GHz. In addition, the repeatability of the algorithms has been proven by measuring a newly designed TE28,10 mode generator cavity. Using the described advanced mode generator system, the quality of the excited modes has been significantly improved and the time for the proper adjustment has been reduced by at least a factor of 10.

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“…To overcoming these issues, a gyrotron using a coaxial insert (coaxial-cavity gyrotron) can be used. The coaxial cavity reduces mode competition and voltage depression [6,7]. The first KIT modular coaxial-cavity pre-prototype gyrotron reached an RF output power of more than 2 MW at 170 GHz in short-pulse operation [8,9].…”

Section: Introductionmentioning

confidence: 99%

Theoretical Study on the Operation of the EU/KIT TE34,19-Mode Coaxial-Cavity Gyrotron at 170/204/238 GHz

Ruess¹,

Avramidis²,

Gantenbein³

et al. 2019

EPJ Web Conf.

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The 170 GHz 2 MW TE34,19-mode coaxial-cavity modular short-pulse pre-prototype gyrotron at KIT was recently modified in order to verify the multi-megawatt coaxial-cavity technology at longer pulses. In parallel, theoretical investigations on a possibility to operate the 170 GHz TE34,19-mode coaxial-cavity prototype at multiple frequencies up to 238 GHz have been started, with a goal to find a configuration at which the tube could operate in the KIT FULGOR gyrotron test facility using the new 10.5 T SC magnet. This paper indicates which adjustments have to be made and show the feasibility of the multi-frequency operation. Small modifications at the gyrotron cavity will support an RF output power of more than 2 MW at 170/204 GHz. Furthermore, a new gyrotron launcher has been designed capable of producing a Gaussian microwave beam with a Gaussian mode content of more than 96% at these frequencies.

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Design Considerations for Powerful Continuous-Wave Second-Cyclotron-Harmonic Coaxial-Cavity Gyrotrons

Cited by 36 publications

References 13 publications

Electromagnetic Analysis of Coaxial Gyrotron Cavity With the Inner Conductor Having Corrugations of an Arbitrary Shape

Electromagnetic Analysis of Coaxial Gyrotron Cavity With the Inner Conductor Having Corrugations of an Arbitrary Shape

Computer-Controlled Test System for the Excitation of Very High-Order Modes in Highly Oversized Waveguides

Theoretical Study on the Operation of the EU/KIT TE34,19-Mode Coaxial-Cavity Gyrotron at 170/204/238 GHz

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