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Journal Articles

Development of ITER equatorial EC launcher components toward the final design

Takahashi, Koji; Kajiwara, Ken; Oda, Yasuhisa; Sakamoto, Keishi; Omori, Toshimichi*; Henderson, M.*

Fusion Science and Technology, 67(4), p.718 - 731, 2015/05

 Times Cited Count:3 Percentile:58.31(Nuclear Science & Technology)

Development of an electron cyclotron (EC) equatorial launcher has been undergoing a series of prototype tests and design enhancements intending to improve reliability and functionality of the launcher. The design enhancements include adaptation of the launcher steering angles such that one of three beam rows of the launcher is necessary flipped to perform counter current drive (to conform to a new ITER physics requirement). Also the top and bottom steering rows have been tilted with angle of 5$$^{circ}$$ so that the top and bottom beam row can access from on axis to near mid-radius. Furthermore, the position of the focusing mirror that forms a quasi-optical in-vessel millimeter wave transmission line is modified to increase the nuclear shielding capability. High power experiment of the mm-wave launching system mock-up fabricated in basis of the design confirmed the successful steering capability of 20$$^{circ}$$$$sim$$40$$^{circ}$$. It was measured that some of stray RF propagated in the beam duct and generated some heat on the duct at a certain condition of mm-wave transmission. Prototype tests also include the fabrication of the blanket shield module and the partial port plug mock-up and have shown no serious technological issue on the fabrication and the cooling functionality.

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:11 Percentile:34.46(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

Design performance of front steering-type electron cyclotron launcher for ITER

Takahashi, Koji; Imai, Tsuyoshi; Kobayashi, Noriyuki*; Sakamoto, Keishi; Kasugai, Atsushi; Hayakawa, Atsuro*; Mori, Seiji*; Mori, Kensuke*

Fusion Science and Technology, 47(1), p.1 - 15, 2005/01

An applicability of a front steering type EC launcher to a fusion reactor is described with the design and thermal, electromagnetic and nuclear analysis using the ITER design conditions. Maximum stress of the support keys of the front shield module, the welds of the keys and the mirror shaft induced by electromagnetic force are 85.5MPa and 34.1MPa and 22MPa, respectively, which are less than 1.5Sm of stainless steel(205MPa). Maximum thermal stress in the front shield module and the mirror, which are 249MPa and 350MPa, respectively, are obtained at the inner surface of a stainless steel cooling tube. The stresses are less 3Sm of stainless steel at 200$$^{circ}$$C(410MPa). The annual neutron fluence and the dose rate at the vacuum window(closure plate) are estimated to be 10$$^{13}$$$$sim$$10$$^{12}$$ n/cm$$^{2}$$/yr and 45$$mu$$Sv/h, respectively that satisfy the shield criteria of the ITER. It appears that the design of the front steering type EC launcher is applicable to an ITER grade reactor.

Journal Articles

Development of EC launcher components for ITER

Takahashi, Koji; Kobayashi, Noriyuki*; Kasugai, Atsushi; Sakamoto, Keishi

Journal of Physics; Conference Series, 25, p.75 - 83, 2005/00

Recent progress of the development on the ITER equatorial EC launcher components, such as the steering mirrors, its drive system, the waveguide components and the diamond vacuum windows, is reported. Thermmo-mechanical analysis of the recent mirror design shows that maximum temperature increase of 187$$^{circ}$$C at the reflecting surface and maximum stress of 242MPa at the inner surface of the cooling tube are obtained. In the cyclic test of the spiral tube mock-up, the cyclic number of 1.3$$times$$10$$^{6}$$ is succeeded without failure. In the window development, the fabrication of the Cu-coated edge diamond window and the high power transmission test were done. The Cu-coating on the disk edge can avoid water ingress in the launcher (vessel) under the assumption of the crack formation toward edge. Transmission experiment indicative to 1.2MW, was carried out. Temperature increase of 50$$^{circ}$$C agrees with the calculation. It concludes that the Cu-coated window is capable of MW-level transmission and improves its reliability.

Journal Articles

Development of EC H&CD launcher components for fusion device

Takahashi, Koji; Ishitsuka, Etsuo; Moeller, C. P.*; Hayashida, Kazunori*; Kasugai, Atsushi; Sakamoto, Keishi; Hayashi, Kenichi*; Imai, Tsuyoshi

Fusion Engineering and Design, 66-68, p.473 - 479, 2003/09

 Times Cited Count:11 Percentile:36.18

For the purpose to confirm the reliability of the front steering concept, tests of the front steering launcher mock-up and neutron irradiation tests of bearings for a movable mirror were carried out under the ITER conditions. The max. stress of the flexible pipes for the movable mirror was measuerd to be 60MPa, much less than the allowable stress and agree with the calculation. No degradation on the performance of bearings was obtained for the assumed fluence of ITER. The mock-up of remote steering(RS) launcher was tested and RF radiation of 0.5MW-3sec and 0.2MW-10sec over 0-10$$^{circ}$$ were performed. No degradation was obseved, either. The new launcher which has the capability of wider range rf beam steering and the corrugated square waveguide with four miter bends that yield the dog-legged structure has been designed, based on the test results. It has been fabricating for high power experiments.

Journal Articles

High power experiments of remote steering launcher for electron cyclotron heating and current drive

Takahashi, Koji; Moeller, C. P.*; Sakamoto, Keishi; Hayashi, Kenichi*; Imai, Tsuyoshi

Fusion Engineering and Design, 65(4), p.589 - 598, 2003/07

 Times Cited Count:20 Percentile:18.93

High power radiation experiments of a remote steering launcher for an EC H&CD system were carried out to study the characteristic of the rf beam steering and transmission. The remote steering launcher consists of a 4.632m corrugated square waveguide (45.7 $$times$$ 45.7mm$$^{2}$$) and a movable flat mirror which is placed at the input of the waveguide. Measurements were made in the range 0-10$$^{circ}$$ at a frequency of 170GHz. The measured radiation pattern is clearly a Gaussian-like distribution, which is in agreement with the low power measurements. A steering capability of up to 10$$^{circ}$$ was experimentally confirmed. Transmission and radiation of 0.5 MW-3.0 sec and 0.2 MW-10.0 sec pulses were successfully demonstrated over a steering angle range of 0-10$$^{circ}$$. No arcing was observed during the experiments and no damage to the waveguide was found after the experiments were finished. We confirmed that remote steering was a possibly alternative scheme of rf beam steering for EC H&CD.

Journal Articles

Transmission experiments of a 170GHz remote steering EC launcher

Takahashi, Koji; Moeller, C. P.*; Kasugai, Atsushi; Minami, Ryutaro; Sakamoto, Keishi; Imai, Tsuyoshi

Proceedings of 28th International Conference on Infrared and Millimeter Waves, p.385 - 386, 2003/00

no abstracts in English

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.

Oral presentation

Modification of ITER equatorial EC launcher design enhancing EC H&CD function

Takahashi, Koji; Abe, Ganji; Isozaki, Masami; Ikeda, Ryosuke; Oda, Yasuhisa; Kajiwara, Ken; Sakamoto, Keishi; Kobayashi, Noriyuki*; Iida, Hiromasa*; Komatsuzaki, Manabu*; et al.

no journal, , 

It was analytically obtained that electron cyclotron current drive efficency at $$rho$$=0.4$$sim$$0.6 can be doubled modifying the steering function of millimeter wave launching from the equatorial port from toroidally to poloidally. The design modification of the ITER equatorial launcher enhancing ECCD function is implemented. The millimeter wave design satisfying transmission efficiency more than 99% with the required ploidal beam steering capability is successfully obtained and reflected to the launcher structural design. The millimeter wave design optimization, BSM design modification to allow the required polidal beam steering capability and so on are reported in detail at the conference.

Oral presentation

Progress in ECH/CD launcher development for JT-60SA

Kobayashi, Takayuki; Hiranai, Shinichi; Sawahata, Masayuki; Terakado, Masayuki; Wada, Kenji; Hinata, Jun; Sato, Fumiaki; Yokokura, Kenji; Hoshino, Katsumichi; Takahashi, Koji; et al.

no journal, , 

A mechanical structure of the launcher for electron cyclotron heating and current drive in JT-60SA has been designed to realize wide range of poloidal and toroidal injection angles with high reliability. One of the key components is a bellows structure (vacuum boundary) enabling linear and rotation motions of the rigid shaft. A full scale mock-up of the bellows structure has been fabricated and tested. The linear motion was repeated 100,000 cycles and the rotation motion was repeated 10,000 cycles. In this test, no evidence of vacuum leakage was observed. Then, the mock-up has been extended up to the first mirror including full length of the steering shaft (~4 m) and bearings. The cyclic test of the full system of the driving structure will be carried out in 2015. A mock-up of M2, which is a large curved mirror including four cooling channels, has been designed and fabricated. It was experimentally confirmed that the flow rate of each cooling channels was consistent with the design.

Oral presentation

Mock-up test results of ITER ECH Equatorial launcher's mm-wave design

Shidara, Hiroyuki; Takahashi, Koji; Komatsuzaki, Manabu*; Isozaki, Masami; Kobayashi, Noriyuki*; Abe, Teruo*; Abe, Ganji; Oda, Yasuhisa; Ikeda, Ryosuke; Kobayashi, Takayuki; et al.

no journal, , 

In order to validate the millimeter wave design procedure, the EL mock-up has been constructed and the low power test has been carried out by using mW-level low power RF oscillators. The test has been carried out with critical four edged beams instead of all eight beams in the upper waveguide unit. The measured data has been compared with design at several important locations in the launcher and after the launcher exit with steering mirror angle changed. The comparison of the measured beams propagation and the design shows good agreement for the beam sizes and the beam orientation performance. The quantitative evaluations has been carried out and the design procedure's reasonability has been confirmed.

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