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As the first divertor tokamak in China, HL-2A device has been successfully operated and stably sustained in the single-null divertor configuration under good feedback control of plasma current and position. Up to now, the following operation parameters have been achieved: Ip = 400 kA, Bt = 2.6 T and discharge duration Td = 2980ms. An excellent repeatability of discharge has been achieved and about 90% Greenwald density limit has been reached. The HL-2A SN divertor configuration can be simulated by the SWEQU code and identified by CCD imaging system and CF code. The experimental results proved that the divertor configuration and siliconization could strongly decrease the plasma radiation and impurity emission and reduce the recycling effectively. Density limit disruption has been analyzed and some interesting phenomena, such as asymmetric cold pulse perturbation and snake-like perturbation, have been observed during Molecular Beam Injection. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

In this paper, the ratios of the volume of the pulse tube and the void volume of the regenerator to the compressor's swept volume are considered as the two most important parameters for a high frequency miniature PTR design. Firstly, knowing the compressor's swept volume, a 1-D numerical simulation is adapted to investigate the effect of the above two ratios on the performance of the miniature PTR. Under the condition of charge pressure of 2.1MPa, 2.5MPa and 2.9MPa, and the operating frequency of 50Hz, it is found that the optimum ratios of the volume of the pulse tube and the void volume of the regenerator to the compressor's swept volume are in the range of 0.8-1.0 and 1.1-1.3, respectively. To verify this conclusion, 25 PTRs using a 1.66cm³ compressor are composed of five different size of regenerators and pulse tubes, and all the PTRs are tested under different charge pressure with operating frequency of 50Hz. The experimental results indicate that the optimum ratios of the volume of the pulse tube and the void volume of the regenerator to the compressor's swept volume are in the range of 0.7-1.0 and 1.0-1.2, respectively. The experimental results agree with the simulated results qualitatively. [ABSTRACT FROM AUTHOR]

It is generally considered that the use of an inertance tube in a high frequency pulse tube refrigerator (PTR) improves the phase shift between the pressure and the mass flow rate. In order to investigate the effects of inertance tubes on the performance of a miniature PTR, experiments on the high frequency miniature PTR with inertance tube, orifice and bypass have been carried out. Inertance tubes with various inner diameters of 0.5mm, 1mm, 1.5mm, 2mm and different lengths from 1m to 7m were tested. Two fine needle valves were adapted as the orifice and the bypass. The experiments were performed under a charge pressure of 2.5MPa. The operating frequency is varied from 20Hz to 50Hz. Experimental results show that the inertance tube with inner diameter of 1.5mm and length of 2m is proper for the miniature PTR at high frequency. The benefit of using only an inertance tube is not apparent in miniature PTR. The lowest temperature achieved by the PTR with inertance tube is only 107.3K, which is higher than the lowest temperature of 101.6K achieved by the bypass PTR. The miniature PTR with both inertance tube and double inlet configuration has the lowest temperature of 89K. It is also found that the bypass configuration has the function of power recovery. [ABSTRACT FROM AUTHOR]

© 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]