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Development of the ECH/CD system for JT-60SA has been progressed. (i) A full length (~7 m) mock-up of the mirror steering structure of the launcher has been successfully tested in vacuum. The required life without maintenance, which is 105 cycles for the poloidal steering range of 60° and 104 cycles for toroidal beam steering range of 30°, has been achieved. A newly introduced solid lubricant enabled the smooth movement of the steering shaft. (ii) The temperature rise distribution of aluminum waveguides has been measured at high-power of 0.5 MW. It is in the range from 0.2 to 1.2 °C per 1 MJ transmission and acceptable for 1 MW/100 s transmission required in JT-60SA. (iii) The preparation of the JT-60SA ECH/CD system toward first plasma experiment is smoothly progressing by the above results and the successful gyrotron development., 27th IAEA Fusion Energy Conference (FEC 2018)

Developments of a two directional beam steering electron cyclotron heating/current drive launcher for JT-60SA have been progressed based on a linear motion antenna concept. A full-scale (~7m) mock-up of the mirror steering structure with two kinds of bellows structures and an in-vessel support structure has been fabricated and tested in vacuum successfully. The support structure consists of a pair of angular ball bearings made of Si3N4 for rotational motion and a linear guide assembled by a rail and a housing made of non-magnetic stainless steel and Si3N4 balls. Solid lubricant has been used for the linear guide and it results in the improvement of the life time by a factor of greater than 10 with respect to the case without lubricant. Considering that the mock-up test results satisfied the requirements for the bellows and support structures (reliable 40 cm linear movement, 105 cycles and angular rotation 30°, 104 cycles), the final design of the launcher is underway targeting the start of its fabrication., 30th Symposium on Fusion Technology (SOFT 2018)

In JT-60SA (Super Advanced), nine sets of evacuated corrugated waveguide transmission lines (60 – 80 m) will deliver high-power millimeter waves generated by nine sets of multi-frequency gyrotrons (1MW each) to four sets of the launchers. Total injection power of 7 MW into plasma is expected by taking into account the transmission loss of 20 – 25% (including loss in a matching optics unit). Toward start of the first plasma experiment in 2020, fabrication of waveguide components is in progress. The waveguide components of gate-valve, dc-break, torus diamond window and pre-load have been newly designed and fabricated. In addition, two types of pumpout tees with a different gap width (1 mm and 2 mm) and cooling/absorbing structure have been fabricated. In order to evaluate high-power transmission capability of these components, the high-power experiment has been carried out by installing 30 m long test transmission line with seven miterbends in the JT-60SA gyrtron room. It is noted that a newly designed pre-load successfully reduced (20 – 50%) the power deposition on the test waveguide components due to the reflected power from the dummy load. This improvement enabled more clear evaluation of the transmission loss of the tested waveguide components as a simulation of the real situation of the transmission line connected to the tokamak. In this presentation, the detailed measurement results of the cooling water temperature and waveguide surface temperatures is reported., US-EU-Japan RF Heating Technology Workshop

An Electron Cyclotron Heating and Current Drive (ECH/CD) system will be used for many experimental purposes in JT-60SA (Super advanced) such as localized electron heating and current drive, instability control, start-up assist and wall cleaning. In preparation for the first plasma experiment in 2020, the development/preparation of the ECH/CD system components are on-going. Based on the successful result on high-power (1 MW), long-pulse (100 s) transmission during the gyrotron development, the design of the waveguide components was finalized. Then the fabrication of the first set of the waveguide transmission line including torus window, gate valve, dc-break, miterbends, polarizer and vacuum pump out has been started. These components will be delivered by the end of March 2018 and will be tested at high-power in 2018. In addition, it was quantitatively confirmed that the maximum temperature rise of the waveguides near miterbends was 1.2 °C/MJ while the minimum temperature rise was 0.2 °C/MJ at the middle part of 12 m-long straight section of the 40m-long waveguide transmission line with 7 miterbends. Note that the waveguides are non-cooled. Considering the above results, a waveguide cooling jacket was designed and tested at high-power. The final design of the cooling system is on-going by taking into account the above results. In addition to the above progress in the transmission line, R&Ds and design/fabrication/test status of the two dimensional steering launcher, control and power supply was reported., 20th Joint Workshop on Electron Cyclotron Emission (ECE) and Electron Cyclotron Resonance Heating (ECRH)