Design of Circular Corrugated Waveguides to Transmit Millimeter Waves at ITER

Doane, J.L.

doi:10.13182/fst08-a1662

Cited by 74 publications

(49 citation statements)

References 20 publications

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“…Olstad et al reported the single miter bends causes 0.42 % of mode conversion from LP01 mode to LP11 mode with 0.05 degree of misalignment of miter bend mirror. [11,14] The waveguide sag due to gravity and junction error also cause mode conversion in TL. Shapiro et al reported the total mode conversion loss in ITER TL (125 m) caused by these effect is -0.075dB.…”

Section: Mode Conversion In Straight Section Of Tl and Assembly Methodsmentioning

confidence: 99%

“…[9] The TL system and its components for ITER are also widely studied and some theoretical and numerical studies even presented the transmission efficiency of mode content in ITER TL. [10][11][12] JAEA has ITER relevant TL test stand and some ITER TL components were examined for high-power operation using 170 GHz gyrotron. This report presents the result of mode content measurement in the JAEA TL test stand and the effect of high power long-pulse operation in TL.…”

Section: Introductionmentioning

confidence: 99%

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A study of mode purity improvement in the ITER relevant transmission line

Oda

Ikeda

Kajiwara

et al. 2015

EPJ Web of Conferences

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Abstract. In JAEA, mode conversion by corrugated waveguide system which is ITER relevant TL system was studied. To evaluate the alignment method for TL assembly, the mode content of middle section of TL was measured while assembly of the TL test stand. Then 5% of LP01 mode purity degradation was found in the long straight section though it was just assembly of 2m straight WGs. Indeed, the mode conversion calculation showed that 5% of mode conversion may occur when the straight section causes 1.0 mm of periodic deflection. To minimize the deflection, the alignment method with adjustment of both position and angle of the WG piece utilizing the laser beam reflection was applied for the TL re-assembling. The mode purity in the same section was improved and mode purity degradation was less than 1%. Finally 93% of LP01 mode purity was achieved at the end of long TL. Next the effect of mode purity by high-power long-pulse operation in TL was studied. Since the TL components are heated during the high-power RF operation, the TL causes deformation due to thermal expansion and deformed TL section induces significant mode conversion loss. The 170GHz gyrotron provided high-power (400kW) and long pulse (500sec) into TL and the beam profile at TL end was measured both before and after the long pulse operation. The mode purity at TL end was 91% before the long pulse and it decreased to 84% after the pulse. The temperature distribution and displacement of TL components were also measured. The measured displacement shows that the vertical sections became S-bend structures and mode conversion loss was estimated. The estimated total mode conversion loss in deformed long TL system was 8%. The estimated value showed good agreement with measurement of mode purity.

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Section: Mode Conversion In Straight Section Of Tl and Assembly Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A study of mode purity improvement in the ITER relevant transmission line

Oda

Ikeda

Kajiwara

et al. 2015

EPJ Web of Conferences

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“…TL components used in the experiments were fabricated in General Atomic. [8][9][10] The gyrotron output beam was coupled into TL using MOU and HE 11 mode content at inlet of TL was 95%. [11] The TL test stand includes 4 miter bends, two waveguide switches, and a couple of polarizers.…”

Section: Development Of Two Frequency Gyrotronmentioning

confidence: 99%

“…Thus the mode conversion loss by 40m long TL with 7 miter bends is estimated as 3.5%. [10,12] Thereby HE 11 mode content at JAEA long range TL output is estimated as 91% while 95% of HE 11 mode content beam was provided into TL input.…”

Section: Ec-17 Workhopmentioning

confidence: 99%

Development of dual frequency gyrotron and high power test of EC components

Oda

Kajiwara

Takahashi

et al. 2012

EPJ Web of Conferences

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Abstract. In JAEA, development of high-power long-pulse gyrotrons is underway. The output power of the gyrotron was applied for high-power long-pulse tests of the transmission line (TL) and the equatorial launcher (EL) mock up for ITER. The feature of design in the dual frequency gyrotron is the simultaneously satisfying the matching of both frequencies at a window and the same radiation angle at an internal mode convertor for both frequencies. The dual frequency gyrotron was developed and high power operations at 170 GHz and 137 GHz were carried out. The 170 GHz high power experiment of 40 m length ITER relevant TL was carried out and transmission efficiency and mode purity change caused by long pulse operation were measured. The mock-up model of EL was also tested using 170 GHz gyrotron. The power transmission through the quasi-optical beam line in EL was demonstrated using the full scale mock up model. Furthermore, the high power test results of the transmission components will be summarized.

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“…A detailed calculation of the Ohmic loss in the straight sections has been given recently by Doane 9 and we have used his estimate in Table 3. The Ohmic loss at a miter bend is given by:…”

Section: Iiib Ohmic Lossmentioning

confidence: 99%

Loss Estimate for ITER ECH Transmission Line Including Multimode Propagation

Shapiro

Kowalski

Sirigiri

et al. 2010

Fusion Science and Technology

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The ITER ECH Transmission Lines (TLs) are 63.5 mm diameter corrugated waveguides that will each carry 1 MW of power at 170 GHz with a transmission efficiency that should exceed 83%. The losses on the ITER TL have been calculated for four possible cases corresponding to having HE 11 mode purity at the input of the TL of 100%, 97%, 90% and 80%. The losses due to coupling, Ohmic and mode conversion loss are evaluated in detail using a numerical code and analytical approaches. Estimates of the calorimetric loss on the line show that the output power is reduced by about 5 ±1 % due to Ohmic loss in each of the four cases. Estimates of the mode conversion loss show that the fraction of output power in the HE 11 mode is about 3% smaller than the fraction of input power in the HE 11 mode. High output mode purity therefore can only be achieved with significantly higher input mode purity. Combining both Ohmic and mode conversion loss, for 1 MW of power generated by the gyrotron, the output power in the HE 11 mode at the end of the ITER TL can be roughly estimated in theory as 920 kW times the fraction of input power in the HE 11 mode.2

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Design of Circular Corrugated Waveguides to Transmit Millimeter Waves at ITER

Cited by 74 publications

References 20 publications

A study of mode purity improvement in the ITER relevant transmission line

A study of mode purity improvement in the ITER relevant transmission line

Development of dual frequency gyrotron and high power test of EC components

Loss Estimate for ITER ECH Transmission Line Including Multimode Propagation

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