Looking forward to the single-stage pulse tube refrigerator

After years of development, the cooling performance has gained rapid development. Cooling capacity 20K nearing 20w, fully meet the requirements of small superconducting magnets, cryogenic pumps cooling, its non Zhejiang University doctoral thesis often broad application prospects. However, the efficiency of the single-stage pulse tube refrigerator is still slightly lower than the single-stage GM refrigerator with temperature zone. For further optimization and research, I believe that should be from the following five aspects:
1) the theoretical calculation of the in-depth development. 20.300 K temperature regenerator simulation analysis, but the refrigerator as a whole, it is necessary to consider the performance of the other major components of the compressor and vascular calculated and the eventual development of a full 20 K single-stage pulse tube refrigerator design calculation methods.
2) phase modulation mode of improvement. The single-stage GM type pulse tube refrigerator with double two-way valve into the gas-phase modulation. The two-way air intake structure of the double valve can be effectively suppressed DC, but it can not completely eliminate the generation of DC. Therefore it is necessary to carry out the four - valve, the inertia tube or other new phase modulation structure.
3) improved rotary valve plane. The composition of the gas distribution system in the rotary valve and compressor is the "heart" of the pulse tube refrigerator. Pulse tube refrigerator with no moving parts in the low temperature side, the rotary valve is the key to its long and stable operation. Experiment using a flat rotary valve wear and torque issues still need to be improved and enhanced.
4) the use of a new cold accumulating material. The storage materials regenerator Er3Ni, lead balls and stainless steel mesh. End at low temperatures (<15 K) of the cold accumulating material, the volume ratio of the heat capacity is smaller than the specific heat capacity of helium. In order to be able to further improve the efficiency of the regenerator, the need to use the regenerator material (e.g. ErPr) having a larger heat capacity at low temperatures. And materials science also need to work closely with the development of new storage materials in the 20 K temperature region with high specific heat.
5) is arranged the way improved. Chillers use a U-shaped arrangement (as shown in Figure 1.8). U-shaped arrangement of simple structure, which makes it easy to produce, but the efficiency is not the best. In order to explore the performance limits of the single-stage pulse tube refrigerator, very necessary to carry out the most efficient linear arrangement.