Status report on CVD-diamond window development for high power ECRH

Thumm, M.; Arnold, A.; Heidinger, R.; Rohde, Magnus; Schwab, R.; Spoerl, Rainer

doi:10.1016/s0920-3796(00)00531-7

Cited by 34 publications

(16 citation statements)

References 2 publications

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“…123,124 Sapphire, the purest alumina grade, and BeO showed no prompt increase in loss, nor with a dose up to 50 MGy. 19,25,[129][130][131][132][133][134] In this context, initial work began to examine both high-purity silicon and diamond homopolar crystalline materials which as a result of their decreasing loss with increasing frequency offered the possibility for operation at frequencies above 150 GHz with loss tangents 10 À5 , at room temperature. Furthermore, these in situ measurements show postirradiation recovery similar to the early reports for proton-and neutron-irradiated materials.…”

Section: Degradation Of Insulator Ac/rf Dielectric Propertiesmentioning

confidence: 99%

Radiation Effects on the Physical Properties of Dielectric Insulators for Fusion Reactors

Hodgson¹,

Shikama²

2012

Comprehensive Nuclear Materials

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Section: Degradation Of Insulator Ac/rf Dielectric Propertiesmentioning

confidence: 99%

Radiation Effects on the Physical Properties of Dielectric Insulators for Fusion Reactors

Hodgson¹,

Shikama²

2012

Comprehensive Nuclear Materials

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“…TE 17,6 at 105 GHz, TE 20,7 at 124 GHz, TE 22,7 at 131 GHz and TE 22,8 at 140 GHz) [13]. Frequencystep tuning is performed by changing the magnetic field and exciting corresponding TE modes in the cavity, while at a fixed magnetic field mainly the acceleration voltage is changed, yielding different RF output power levels.…”

Section: Experimental Set_upmentioning

confidence: 99%

“…[2,3,4]). Frequency step-tunable gyrotrons (beyond the dual frequency range) are not standard products since these broadband tubes require additional optimization of the key components, namely the electron beam forming optics, interaction cavity, quasi-optical mode converter and output window [5,6]. The design of the output window of a frequency step-tunable gyrotron is a particular challenge since it has to provide operation of the gyrotron at different frequencies with minimum reflection of the RF waves.…”

mentioning

confidence: 99%

First Operation of a Step-Frequency Tunable 1-MW Gyrotron With a Diamond Brewster Angle Output Window

Gantenbein

Samartsev

Aiello

et al. 2014

IEEE Trans. Electron Devices

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Abstract-Experimental results using a step-frequency tunable D-band gyrotron are reported. The short-pulse (~3 ms) gyrotron is equipped with an elliptically brazed CVD diamond Brewster angle output window. It is designed for the operation in the frequency range from 111.6 GHz up to 165,7 GHz. Operating parameters for 10 different frequencies corresponding to an equal number of different cavity operating modes has been measured. A minimum output power of 830 kW and a peak output power of 1.3 MW have been realized. For all frequencies the parameters of the RF beam generated by the internal quasioptical converter, such as fundamental Gaussian contents and beam waist, are sufficiently good to allow an efficient coupling of the RF power out of the window. This is the first time a diamond Brewster angle window has been used in a high power gyrotron (~ 1 MW). Such a system offers the path to a simple and compact window solution for high power broadband applications using gyrotrons.

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“…The high fracture stress, though its decrease with disk thickness and grain size, makes the CVD-diamond window capable to bear a high pressure without failure also utilizing a thin disk of dielectric. Negative effects of neutron irradiation are observed in [2] only at a fluence level of 10 22 n/m 2 : the dielectric loss increases and the thermal conductivity pass from 1800 W/mK to 200 W/mK. All these features made this material the best choice for use as output windows of 1 MW CW gyrotrons in ECRH systems.…”

Section: Introductionmentioning

confidence: 99%