[en] Highlights: • A steady-state data acquisition system for ECRH on EAST tokamak is developed. • Both hardware architecture and software architecture are described. • The data acquisition system is very important for gyrotron operation. - Abstract: A steady-state data acquisition system for electron cyclotron resonance heating on EAST tokamak is presented. This system is established to acquire gyrotron related signals based on PXI platform. The acquired signals are used to analyze the state of gyrotrons, and to calculate the RF power generated by gyrotrons. The acquired data are saved to the data storage server and can be recalled by the data view client.

[en] In this paper, the measurement method of calorimetric power for an electron cyclotron resonance heating (ECRH) system for EAST is presented. This method requires measurements of the water flow through the cooling circuits and the input and output water temperatures in each cooling circuit. Usually, the inlet water temperature stability is controlled to obtain more accurate results. The influence of the inlet water temperature change on the measurement results is analyzed for the first time in this paper. Also, a novel temperature calibration method is proposed. This kind of calibration method is accurate and effective, and can be easily implemented. (paper)

[en] Highlights: • Two single-frequency 140 GHz gyrotrons are planned to be repaired to restore the performance to a good state for EAST. • The gyrotrons will be upgraded to have the output capability of 0.6 MW/1 MW at 105 GHz/140 GHz. • The upgraded ECRH system will be used for future EAST experiments to explore the range of low q₉₅ and high β_N. The ECRH (Electron Cyclotron Resonance Heating) system was used in the EAST (Experimental Advanced Superconducting Tokamak) experiments for several years, and some good experimental results have been obtained. However, the performance of the gyrotrons is degraded and the ability to stabilize output RF (Radio Frequency) power is reduced. Two single-frequency 140 GHz gyrotrons are planned to be repaired in order to improve the performance of the gyrotrons. At the same time, some internal components of the gyrotrons (such as collectors, electron guns, mode conversion mirrors) will be upgraded to make the gyrotrons have the output capability of 0.6 MW/1 MW at 105 GHz/140 GHz. The MOUs (Matching Optical Units), transmission lines, the low voltage power supplies, the measurement and control system, and the water-cooling system also need to be modified for the dual-frequency operation of the new gyrotrons. The retrofitted design of the EAST ECRH system using dual-frequency gyrotrons is discussed in the paper. The upgraded ECRH system will be used for future EAST experiments to explore the range of low q₉₅ and high β_N, to study the steady-state operation mode for the future nuclear fusion power plants.

[en] The power supply system and polarization feedback control system are core components of the entire electron cyclotron resonance heating system (ECRH). In order to ensure the stable and reliable operation of the electron cyclotron system, the electron cyclotron resonance heating wave parameter control system is designed based on the graphical programming language Lab View not only to monitor and control the superconducting magnet power supply, the anode power supply and the filament power supply, but also to set basic parameters such as power supply voltage and current. And under the synergy of the calculation program such as TORAY, as well as the parameters calculated by it like beam incident angle, the absorption of the electron cyclotron wave to plasma is promoted. (authors)

[en] In this paper, we design a mode converter that can convert the TE10 rectangular waveguide mode into TE01 circular waveguide mode. It is used in the thin film deposition in electron cyclotron resonance (ECR) technology, so the microwave power will keep a particular pattern distribution in the reaction chamber and work together with the magnetic field to produce plasma. The magnetron center frequency of output power is 915 MHz. In order to avoid the motivation of the spurious modes, improve the conversion efficiency and keep the bandwidth unchanged, we use HFSS to optimize the structure. The resulted conversion efficiency is about 99.90% at 915 MHz. The conversion efficiency is bigger than 99.00% within the scope of the center frequency of 20 MHz, it satisfies with the requirements. (authors)

[en] A monitoring and control system for the ECRH superconducting magnet device is designed to ensure the stable and reliable operation of the ECRH superconducting magnet device. The monitoring and control system uses the computer network technology and the optical fiber isolation technology, and utilizes the graphical programming software LabVIEW to design the interface to set the parameters such as the superconducting magnet current, voltage and so on, monitor the state of the superconducting magnet and its hardware device in real time. Once the superconducting magnet quenching is detected or the hardware devices failure occurs, the chain protection will be triggered to ensure the stable operation of the superconducting magnet device and the entire ECRH system. (authors)

[en] The Phase-shifted Full-bridge Zero-Voltage Switching topology was used to design a high-power gyrotron filament power supply with output voltage feedback. This paper introduced the architecture of the power supply, calculation process of key parameters, output voltage control circuit and the advantages of the output voltage control circuit. At the end of this paper, the main waveforms and key parameters of the prototype were measured, and the stability was verified by the aging test. (authors)

[en] A 140GHz electron cyclotron resonance heating and current drive (EC H and CD) project for EAST Tokamak is launched in 2011 with a total power of 4MW and pulse length of 100 s. The main objectives of the system are to provide central H and CD, assist start-up and control of MHD activities. The system comprises four gyrotrons each with nominal output power of 1MW at 140GHz. The RF power, transmitted through four evacuated corrugated waveguides will be injected into plasma from the low field side (radial port). The front steering equatorial launcher directs the RF beam over ±25° toroidally and scans over 38° poloidally. At present, the construction of the first 1MW system is undergoing for the expected campaign in the end of 2013. In this paper, the current status of the development and the design of the 140-GHz ECRH system are presented

[en] Highlights: • The new constructing 140 GHz/1 MW/1000 s ECRH system was briefly introduced and the structure of ECRH launcher was detailedly described. • The transmission characteristics of the RF propagation inside the launcher were calculated and the Gaussian beam radius in the resonance layer of plasma was optimized. • Temperature distribution and thermal-stress of mobile mirror were analyzed. • The inner equivalent diameter of water channel in the mobile mirror and the suggested water velocity were analyzed. - Abstract: EAST is a medium sized superconducting tokamak with major radius R = 1.8 m, minor radius a = 0.45 m, plasma current I_p ≤ 1 MA, toroidal field B_T ≤ 3.5 T and expected plasma pulse length up to 1000 s. An electron cyclotron resonance heating (ECRH) launcher for four-beam injection is being installed on EAST tokamak. Four electron cyclotron wave beams which are generated from four sets of 140 GHz/1 MW/1000 s gyrotrons will be injected into the plasma by the spherical focusing mirrors and plane mobile mirrors. The focusing mirrors are spherical to focus Gaussian beams after reflection. Four plane mobile mirrors independently steer continuously in the poloidal and toroidal direction controlled by motors. With the suitable distance between mirrors and appropriate focal length of focusing mirror, the beam radius in the resonance layer of plasma is 31.145 mm. The heat from plasma radiation and metal losses is loaded on the mobile mirror. In order to decrease the temperature and thermal stress, the inner equivalent diameter of water channels is 8 mm and the suggested water velocity is 4 m/s

[en] A long pulse electron cyclotron resonance heating (ECRH) system has been developed to meet the requirements of steady-state operation for the EAST superconducting tokamak, and the first EC wave was successfully injected into plasma during the 2015 spring campaign. The system is mainly composed of four 140 GHz gyrotron systems, 4 ITER-Like transmission lines, 4 independent channel launchers and corresponding power supplies, a water cooling, control and inter-lock system etc. Each gyrotron is expected to deliver a maximum power of 1 MW and be operated at 100-1000 s pulse lengths. The No.1 and No.2 gyrotron systems have been installed. In the initial commissioning, a series of parameters of 1 MW 1 s, 900 kW 10 s, 800 kW 95 s and 650 kW 753 s have been demonstrated successfully on the No.1 gyrotron system based on calorimetric dummy load measurements. Significant plasma heating and MHD instability suppression effects were observed in EAST experiments. In addition, high confinement (H-mode) discharges triggered by ECRH were obtained. (paper)