[en] Given the deficiency of the monitoring system in 4 MW/2.45 GHz LHCD, a new layer-based mode of the software monitoring is formulated for 6 MW/4.6 GHz LHCD system, which intends to provide better scalability. Both the monitor server and monitor client are implemented after solution to inter-process and network communication was brought out by taking advantage of QProcess and QTcpSocket classes in cross-platform developing framework Qt. The response time of the new software monitoring system proves to be less than 200 ms after practical test and able to fully satisfy the requirements of 4.6 GHz LHCD to monitor software devices within 2 s. (authors)

[en] To test high power klystrons and microwave components used in Lower Hybrid Current Drive (LHCD) system for EAST tokamak, a new kind of C-band continuous wave high power water load has been designed, deionized water sealed with beryllia ceramic is used as the microwave absorbent. Low power test results show that, in the (4600 ± 50)MHz frequency range, the Voltage Standing Wave Ratio (VSWR) is below 1.1, high power test resulted in 250 kW being absorbed for 1600 s with less than 1.0 kW power reflection, the water temperature difference between inlet and outlet is about 17.6 ℃ at 250 kW power level, while the water flow rate is 203.3 L/min. (authors)

[en] A filament is a critical component of the klystron used to heat the cathode. There are totally 44 klystrons in experimental advanced superconducting tokamak (EAST) lower hybrid current drive (LHCD) systems. All klystron filaments are powered by AC power suppliers through isolated transformers. In order to achieve better klystron preheat, a klystron filament power supply control system is designed to obtain the automatic control of all filament power suppliers. Klystron filament current is measured by PLC and the interlock between filament current and klystron high voltage system is also implemented. This design has already been deployed in two LHCD systems and proves feasible completely.

[en] A triple Langmuir probe was installed at the top of the lower hybrid (LH) antenna in the experimental advanced superconducting tokamak (EAST). The probe system consists of a triple probe, a measurement circuit, data acquisition and data processing. The preliminary results show that injection of LH power increases the density in front of the LH grill. The relationship between grill densities and reflection coefficients (RCs) agrees with the theoretical prediction. The optimum density for LH coupling in EAST was measured, being in range of (4 ∼ 5 × 10"1"7m"-"3. (authors)

[en] Objective: To compare the difference between volume computed tomography dose index (CTDI_vol) and size-specific dose estimates (SSDE) in evaluating the radiation dose of abdominal CT scan. Methods: Abdominal CT scan were performed on 180 patients with a Philips 256-slices spiral CT. The anterior-posterior dimension (AP) and lateral dimension (LAT) of each patients were measured at the level of left renal vein, and the effective diameter (ED) and SSDE were calculated with recorded CTDI_vol Patients were categorized into 3 groups depending on body mass index(BMI): group A, BMI < 20.0 kg/m²; group B, 20.0-24.9 kg/m²; group C, BMI > 24.9 kg/m². The differences between CTDI_vol and SSDE of 180 patients and three different BMI groups were compared respectively. Results: There was a significant difference between CTDI_vol and SSDE of the 180 patients (t = -13.354, P < 0.01), CTDI_vol and SSDE were (9.91 ± 2.91) and (14.01 ± 2.82) mGy, respectively. For group A, CTDI_vol and SSDE were (7.96 ± 1.83) and (12.83 ± 2.52) mGy, respectively (t = -8.417, P < 0.01). Group B, CTDI_vol and SSDE were (9.28 ± 1.76) and (13.62 ± 2.18) mGy, respectively (t = -15.051, P < 0.01). Group C, CTDI_vol and SSDE were (12.19 ± 3.65) and (15.39 ± 3.47) mGy, respectively (t = -4.535, P < 0.01). In addition, the mean percentage values of difference between CTDI_vol and SSDE for the three groups were 62.83%, 47.80%, 28.40%, respectively, which meant CTDI_vol underestimated the radiation dose compared to SSDE. With the BMI increasing, the values of difference between CTDI_vol and SSDE decreased. Conclusions: SSDE can be used to estimate the radiation dose of abdominal CT scan for a given size person. (authors)

[en] Experimental Advanced Superconducting Tokamak (EAST), as a fully superconducting tokamak in China, aims to achieve high performance plasma under steady-state operation. To fulfill the physical objectives of EAST, a program of 4-MW long pulse electron cyclotron resonance heating and current drive (EC H&CD) system, which would offer greater flexibility for plasma shape and plasma stabilization has been launched on EAST since 2011. The system, composed of 4 gyrotrons with nominal 1MW output power and 1000s pulse length each, is designed with the feature of steerable power handling capabilities at 140 GHz, using second harmonic of the extraordinary mode(X2). The missions of the ECRH system are to provide plasma heating, current drive, plasma profile tailoring and control of magneto-hydrodynamic (MHD) instabilities. Presently, the first two 140-GHz 1-MW gyrotrons, provided by GYCOM and CPI, respectively, have been tested at long pulse operation. The tubes, the associated power supplies, cooling system, cryogenic plant, 2 transmission lines and an equatorial launcher are now installed at EAST. The power generated from each tube will be transmitted by an evacuated corrugated waveguide transmission line and injected into plasma from the low field side (radial port) through a front steering equatorial launcher. Considering the diverse applications of the EC system, the beam’s launch angles can be continuously varied with the optimized scanning range of over 30° in poloidal direction and ±25° in toroidal, as well as the polarization could be adjusted during the discharge by the orientations of a pair of polarizers in the transmission line to maintain the highest absorption for different operational scenarios. The commissioning of the first 2MW ECRH plant for EAST is under way. The design, R&D activities and recent progress of the long pulse 140-GHz ECRH system are presented in this paper. As the technological requirements for EAST ECRH have many similarities with ITER devices, the installation and experience of EAST ECRH system may provide valuable data for the ITER