Frequency step-tunable (114–170 GHz) megawatt gyrotrons for plasma physics applications

As an attractive auxiliary heating method for J-TEXT, ECRH systems composed of six 200 kW/60 GHz subsystems are under development. The main components of these systems are donated by the Culham Science Center. To rebuild these systems on the site of J-TEXT, a superconducting magnet (SCM) system for the 60 GHz gyrotron has been firstly tested. The SCM consists of two cavity coils, a gun coil and two pairs of trim coils, where the magnetic field is mainly generated by the cavity coils. To confirm the condition of this SCM, firstly vacuum leak detection was done and the resistance variation of the whole coils during cooling was monitored. Then the transverse and axis fields of the SCM were measured with a designed three-dimensional magnetic field measurement device; the measured axis field was compared with the results calculated by the finite element method. Finally, considering the safety of persons and electrical equipments when the SCM is charged, the stray field was detected. The test results indicate that the condition of this SCM is good and can be used for the 60 GHz gyrotron.

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“…1), where the millimeter wave is excited. The relationship between the frequency f w of the wave and B z0 is as follows [10]:…”

Section: Magnetic Field Sensorsmentioning

confidence: 99%

Commissioning of a 60 GHz Gyrotron Superconducting Magnet System on J-TEXT Tokamak

et al. 2015

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“…Parallel to the development of a frequency step tunable gyrotron [6] the procurement of a superconducting magnet had been started at KIT, together with the corresponding power supplies. The aim is to achieve a quick frequency change at a rate of 6.6 GHz/s, with a repetition-rate of 1 every 10 seconds.…”

Section: Cryomagnet For Frequency Step Tunable Gyrotronmentioning

confidence: 99%

Technical developments at the KIT gyrotron test facility

Schmid

Erckmann

Gantenbein

et al. 2011

Fusion Engineering and Design

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Parasitic beam tunnel oscillations have been discovered on all gyrotrons currently being developed and tested at KIT (1MW/140 GHz tube for W7-X, 2 MW/170 GHz coaxial gyrotron and 105-143 GHz frequency step tunable gyrotron). In the case of the W7-X gyrotrons these problems have been observed only on some of the series production tubes. A modified beam tunnel design, technologically close to the old design, has successfully been tested on both the coaxial and f-step-tunable gyrotrons and has subsequently been implemented on one of the W7-X series-production-tubes presently undergoing factory acceptance tests in Karlsruhe.The ECRH test loads at KIT are operated under normal atmospheric conditions. Several loads have eventually failed in 1 MW long pulse experiments and KIT has therefore started to design its own loads. The first KIT-load is based on a fixed conical mirror and a cylindrical aluminum absorber coated with a lossy material. The new load was very economical to manufacture and has so far successfully been used during the acceptance tests of two 1-MW CW gyrotrons. Nevertheless a new load based on (uncoated) stainless steel absorbers is being developed as a backup solution for the ongoing high priority gyrotron testing.A superconducting magnet capable of rapid field changes between 4.15 and 5.67 Tesla for frequency steptunable gyrotrons has been procured, has achieved its specified maximum (static) field of 7.2 Tesla and has also demonstrated its capability of rapid field-changes. Final acceptance however has been delayed pending rectification of problems with the magnetic field alignment.

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“…The availability of sources with fast frequency tunability (several GHz s −1 , tuning in 1.5-2.5% steps for approximately ten different frequencies) would permit the use of a simple, fixed non-steerable mirror antenna for local ECCD experiments and plasma stabilization [21,42]. Challenges in this development are the proper MIG as well as the broadband QO output coupler and CVD diamond window.…”

Section: Development Of Advanced Fusion Gyrotronsmentioning

confidence: 99%

“…Successful gyrotron experiments at KIT Karlsruhe employing a 140 GHz, TE 22,6 -mode cavity, a QO mode converter with dimple-type launcher, a broadband silicon nitride composite Brewster angle window and a SDC gave up to 1.6 MW output power (pulse duration: 1-5 ms) at efficiencies between 48 and 60% for the entire operating mode series in the frequency range from 114 GHz to 166 GHz (TE m,5 with m=18 to 22, TE m,6 with m=20 to 26 and TE m,7 with m=22 to 26) [42]. Frequency tuning in steps of approximately 3.7 GHz was achieved by variation of the magnetic field strength in the cavity [46].…”

Section: B Tunable Multi-frequency Gyrotronsmentioning

confidence: 99%

Recent Developments on High-Power Gyrotrons—Introduction to This Special Issue

Thumm

2010

J Infrared Milli Terahz Waves

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Gyrotrons with output powers of several 100 kW are mainly used as high-power millimeter (mm)-wave sources for electron cyclotron resonance heating (ECRH), electron cyclotron current drive (ECCD), stability control and diagnostics of magnetically confined plasmas for generation of energy by controlled thermonuclear fusion. Other applications include ECR ion sources, materials processing and plasma chemistry, high-resolution Doppler radar, radar ranging and imaging in atmospheric and planetary science, active denial systems, as well as detection of concealed radioactive materials. The present review summarizes the status of recent developments on high-power gyrotrons and introduces this Special Issue on Gyrotrons.

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Frequency step-tunable (114–170 GHz) megawatt gyrotrons for plasma physics applications

Cited by 104 publications

References 12 publications

Commissioning of a 60 GHz Gyrotron Superconducting Magnet System on J-TEXT Tokamak

Commissioning of a 60 GHz Gyrotron Superconducting Magnet System on J-TEXT Tokamak

Technical developments at the KIT gyrotron test facility

Recent Developments on High-Power Gyrotrons—Introduction to This Special Issue

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