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Journal Articles

Innovation on high-power long-pulse gyrotrons

Litak, A.*; Sakamoto, Keishi; Thumm, M.*

Plasma Physics and Controlled Fusion, 53(12), p.124002_1 - 124002_14, 2011/12

 Times Cited Count:27 Percentile:77.86(Physics, Fluids & Plasmas)

Journal Articles

Design of electron cyclotron heating and current drive system of ITER

Kobayashi, Noriyuki; Bigelow, T.*; Bonicelli, T.*; Cirant, S.*; Denisov, G.*; Heidinger, R.*; Henderson, M.*; Hogge, J.-P.*; Piosczyk, B.*; Ramponi, G.*; et al.

AIP Conference Proceedings 933, p.413 - 416, 2007/10

Since the EDA 2001, Design of Electron Cyclotron Heating and Current Drive (ECH&CD) System have been modified due to progress of physics understanding and change of interface. Nominal RF power 20 MW is injected by four upper launchers or one equatorial launcher. RF beams are steered by a front steering mirror. DCHV power supply will be composed of IGBT pulse step modulators because of high frequency modulation and design flexibility to three different types of 170 GHz gyrotrons from three parties. The RF power is transmitted by 63.5 mm dia corrugated waveguide and switched by a waveguide switch between the upper launcher and the equatorial launcher. A start-up system for initial discharge is composed of three 127.5 GHz gyrotrons and dedicated DCHV power supply. Three of transmission lines are shared between 170 GHz and 127.5 GHz gyrotrons to inject start-up RF beam through the equatorial launcher. R&Ds for high power long pulse have been on-going to obtain a reliable ITER ECH&CD system.

Journal Articles

Development of reliable diamond window for EC launcher on fusion reactors

Takahashi, Koji; Illy, S.*; Heidinger, R.*; Kasugai, Atsushi; Minami, Ryutaro; Sakamoto, Keishi; Thumm, M.*; Imai, Tsuyoshi

Fusion Engineering and Design, 74(1-4), p.305 - 310, 2005/11

 Times Cited Count:13 Percentile:68.06(Nuclear Science & Technology)

A new diamond window with the copper-coated edge for an EC launcher is developed. The diamond window is designed to cool its disk edge. Since Cu is coated at the entire edge, ingress of cooling water into a transmission line in case of failure on the edge is negligible. In addition, corrosion of Al blaze between the edge and the Inconel cuffs can be avoided. A 170GHz, RF transmission experiment equivalent to a MW-level transmission was carried out to investigate the capability of the edge cooling. The transmission power and pulse are 55kW and 3sec, respectively. Temperature increase was 45$$^{circ}$$C and alomost became constant. Thermal calculation with tan$$delta$$ of 4.4$$times$$10$$^{-4}$$ and thermal conductivity of 1.9kW/m/K agrees with the experiment. Since tan$$delta$$ of the diamond is much higher than the actual one (tan$$delta$$=2$$times$$10$$^{-5}$$), the temperature increase corresponds to that of 1MW transmission. It concludes that the Cu coating dose not degrade the edge cooling capability and improves the reliability of the diamond window.

Journal Articles

Development of EC launcher and diamond window for ITER

Takahashi, Koji; Sakamoto, Keishi; Imai, Tsuyoshi; Kasugai, Atsushi; Heidinger, R.*; Thumm, M.*; Moeller, C. P.*

Proceedings of IAEA TM on ECRH Physics and Technology for ITER (CD-ROM), 7 Pages, 2003/00

A front steering (FS) launcher and a remote steering (RS) one have been studied for ITER. In the analysis of a mirror(Cu alloy) for FS launcher, max. temperature of 333$$^{circ}$$C and max. induced stress of 136MPa, less than allowable stress(200MPa), were obtained at the mirror surface under 1MW/1line in CW operation. The efficient transmission ($$eta$$$$>$$95%) at -12$$^{circ}$$$$<$$$$theta$$$$<$$12$$^{circ}$$ and 170GHz was performed for both polarizations in the experiments of a square corrugated waveguide for the RS launcher. RF and pressure tests of the diamond window irradiated by neutron were carried under JA/EU(FZK) collaboration. Neutron fluence of the window was 10$$^{21}$$n/m$$^{2}$$, whereas the estimated annual fluence at the window position is 10$$^{18}$$$$sim$$10$$^{19}$$n/m$$^{2}$$. Transmission of 0.48MW-30sec and 0.2MW-132sec were performed. It was successfully demonstrated that the irradiated window withstood 0.4MPa, which was twice higher than the ITER requirement. Diamond windows are applicable for ITER.

Journal Articles

ITER R&D: Auxiliary systems; Electron cyclotron heating and current drive system

Imai, Tsuyoshi; Kobayashi, Noriyuki*; Temkin, R.*; Thumm, M.*; Tran, M. Q.*; Alikaev, V.*

Fusion Engineering and Design, 55(2-3), p.281 - 289, 2001/07

 Times Cited Count:52 Percentile:95.72(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Chemical vapor deposition diamond window for high-power and long pulse millimeter wave transmission

Kasugai, Atsushi; Sakamoto, Keishi; Tsuneoka, Masaki; *; Imai, Tsuyoshi; Braz, O.*; Thumm, M.*; J.R.Brandon*; R.S.Sussman*; A.Beale*; et al.

Review of Scientific Instruments, 69(5), p.2160 - 2165, 1998/05

 Times Cited Count:64 Percentile:95.19(Instruments & Instrumentation)

no abstracts in English

Journal Articles

High-power millimeter-wave transmission through CVD diamond

Braz, O.*; Thumm, M.*; Kasugai, Atsushi; Sakamoto, Keishi; Takahashi, Koji; Tsuneoka, Masaki; Imai, Tsuyoshi

22nd International Conference on Infrared and Millimeter Waves Conference Digest, p.144 - 145, 1997/00

no abstracts in English

Journal Articles

High power 170 GHz test of CVD diamond for ECH window

Braz, O.*; Kasugai, Atsushi; Sakamoto, Keishi; Takahashi, Koji; Tsuneoka, Masaki; Imai, Tsuyoshi; Thumm, M.*

International Journal of Infrared and Millimeter Waves, 18(8), p.1495 - 1503, 1997/00

 Times Cited Count:38 Percentile:87.17(Engineering, Electrical & Electronic)

no abstracts in English

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