CN222912016U - Active phase modulation type GM pulse tube refrigerator - Google Patents

Abstract

The utility model discloses an active phase-adjusting GM pulse tube refrigerator, including an active phase-adjusting mechanism, a cold finger assembly, a compressor and a phase-adjusting connecting pipe. The active phase-adjusting mechanism is connected to the cold finger assembly through the phase-adjusting connecting pipe, and the cold finger assembly is connected to the compressor through a helium tube, wherein a rotary valve is also provided on the helium tube; the active phase-adjusting mechanism includes a phase-adjusting piston, and a cylinder is provided on the outer side of the phase-adjusting piston; the active phase-adjusting linear motor drives the phase-adjusting piston to perform axial reciprocating motion, wherein the phase-adjusting piston can reciprocate in the cylinder to form a pressure wave. The active phase-adjusting mechanism of the present application is driven by a linear motor, and the phase, displacement and frequency of the phase-adjusting piston are controlled by adjusting the motor parameters to achieve active phase adjustment, so that the mass flow at the hot end of the pulse tube and the pressure wave reach the optimal phase angle, and the efficiency of the whole machine is achieved. A low-frequency active phase-adjusting mechanism is adopted, and the acoustic power of the hot end of the pulse tube can be recovered while actively phase-adjusting, further improving the efficiency of the whole machine.

Description

Active phase modulation type GM pulse tube refrigerator

Technical Field

The utility model relates to the technical field of refrigerators, in particular to an active phase modulation type GM pulse tube refrigerator.

Background

Along with the rapid development of modern scientific technologies such as aerospace, quantum computing and infrared detection technologies, the development and development of low-temperature refrigeration technologies are promoted. The pre-stage pre-cooling system for quantum calculation and quantum communication needs a low-temperature refrigerator with long service life and low vibration interference, mainly uses a GM pulse tube refrigerator, and has different refrigerator types of single stage, multiple stages and the like according to different cold energy and temperature areas. The pulse tube refrigerator has the advantages of simple structure, no moving parts of the cold finger assembly, high reliability, long service life, low vibration interference and the like, but the traditional pulse tube refrigerator has the problems of lower efficiency and the like, and cannot meet the current engineering requirements.

Therefore, the problem of low efficiency of the pulse tube refrigerator is solved, the efficiency of the traditional pulse tube refrigerator is lower than that of the Stirling refrigerator, and the traditional pulse tube refrigerator is lower than that of the Stirling refrigerator because the sound power at the hot end cannot be recovered through a moving ejector or piston like the Stirling refrigerator, but is dissipated in the form of waste heat at a phase modulation mechanism of an inertia tube, a bidirectional air inlet tube and the like, and the refrigeration efficiency can be improved by utilizing a power recovery technology path, so that the disadvantage of low pulse tube refrigeration efficiency is overcome.

Most of the phase modulation mechanisms of the existing GM pulse tube refrigerator are of a bidirectional air inlet type or a small hole phase modulation type and a phase modulation mode combining the two, a circulation flow is easily formed between a pulse tube and a heat regenerator to cause unstable refrigeration temperature, namely a direct current phenomenon, and in addition, because hot end sound power is dissipated in waste heat form at the phase modulation mechanisms of a bidirectional air inlet tube, a small hole and the like, the efficiency of the pulse tube refrigerator is low.

Disclosure of utility model

The utility model aims to solve the technical problem of providing a low-frequency active phase modulation mechanism which can recover the hot end sound work while actively modulating the phase, thereby greatly improving the refrigeration efficiency.

In order to solve the technical problems, the utility model provides the following technical scheme:

The active phase modulation type GM pulse tube refrigerator comprises an active phase modulation mechanism, a cold finger assembly, a compressor and a phase modulation connecting tube, wherein the active phase modulation mechanism is connected to the cold finger assembly through the phase modulation connecting tube, the cold finger assembly is connected to the compressor through a helium tube, and the helium tube is further provided with a rotary valve;

the active phase modulation mechanism comprises a phase modulation piston, a framework is connected above the phase modulation piston, an active phase modulation linear motor is arranged on the outer side of the framework, a cylinder is arranged on the outer side of the phase modulation piston, and the active phase modulation linear motor is arranged on the cylinder;

The active phasing linear motor drives the phasing piston to axially reciprocate, and the phasing piston can reciprocate in the cylinder to form pressure waves.

The active phase modulation mechanism is a low-frequency active phase modulation mechanism driven by a linear motor, forms an alternating magnetic field under the action of alternating current, drives a phase modulation piston to reciprocate, can control alternating current parameters to adjust the phase, displacement and operating frequency of the phase modulation piston to realize an active phase modulation function, has adjustable size, weight, phase modulation connecting tube length and diameter size, obtains the optimal phase angle of pressure waves and mass flow at the hot end of a pulse tube through matching and adjustment of all parameters, thereby improving the efficiency and realizing the high efficiency of the whole machine, and can recover the acoustic power at the hot end of the pulse tube while actively modulating the phase by adopting the low-frequency active phase modulation mechanism, further improving the efficiency of the whole machine, and further realizing the GM pulse tube refrigerator with high reliability and high refrigeration efficiency.

The active phase modulation mechanism comprises a single-piston active phase modulation mechanism and a double-piston opposite active phase modulation mechanism;

In the single-piston active phasing mechanism, a phasing component formed by the active phasing linear motor, the phasing piston, the cylinder and the framework is arranged in a shell of the single-piston active phasing mechanism;

In the double-piston opposite active phase modulation mechanism, the cylinder is replaced by an opposite cylinder, and phase modulation assemblies formed by an active phase modulation linear motor, a phase modulation piston and a framework are symmetrically arranged in a shell of the double-piston opposite active phase modulation mechanism.

In the double-piston opposite active phase modulation mechanism, a compression cavity is formed between two groups of phase modulation components, and a back pressure cavity is formed between the outer ends of the two groups of phase modulation components and the shell.

The active phase modulation linear motor comprises an inner stator, an outer stator, a coil and magnetic steel, wherein the magnetic steel is adhered to a framework, the inner stator is fixed on the outer circle of a thin wall of a cylinder, and the outer stator is sleeved on the coil and is fixed on the end face of a flange of the cylinder.

The magnetic steel can drive the phase modulation piston connected with the coil to axially reciprocate under the action of alternating magnetic force.

As a further scheme of the utility model, the cold finger assembly adopts a primary cold finger assembly, the primary cold finger assembly comprises a primary heat regenerator hot end heat exchanger, a primary heat regenerator cold end heat exchanger, a primary connecting pipe, a primary pulse tube cold end heat exchanger, a primary pulse tube and a primary pulse tube hot end heat exchanger which are sequentially connected, the primary heat regenerator hot end heat exchanger is connected with a primary helium pipe, and the primary pulse tube hot end heat exchanger is connected with a phase modulation connecting pipe.

As a further scheme of the utility model, the first-stage heat regenerator is filled with cold storage materials.

As a further scheme of the utility model, the first-stage cold finger assembly and the second-stage cold finger assembly are used simultaneously, the compressor can be respectively connected into the first-stage cold finger assembly and the second-stage cold finger assembly through the first-stage helium pipe and the second-stage helium pipe, and the first-stage cold finger assembly and the second-stage cold finger assembly are both connected to corresponding active phase modulation mechanisms through phase modulation connecting pipes.

As a further scheme of the utility model, the active phase modulation mechanism adopts a double-piston opposite active phase modulation mechanism.

The secondary cold finger assembly comprises a secondary heat regenerator hot end heat exchanger, a secondary first section heat regenerator, a precooling heat exchanger, a secondary second section heat regenerator, a secondary heat regenerator cold end heat exchanger, a secondary connecting pipe, a secondary pulse tube cold end heat exchanger, a secondary pulse tube and a secondary pulse tube hot end heat exchanger which are sequentially connected, wherein the secondary heat regenerator hot end heat exchanger is connected with a secondary helium tube, and the secondary pulse tube hot end heat exchanger is connected with a phase modulation connecting pipe.

Compared with the prior art, the utility model has the beneficial effects that:

The active phase modulation mechanism is a low-frequency active phase modulation mechanism driven by a linear motor, forms an alternating magnetic field under the action of alternating current, drives a phase modulation piston to reciprocate, can control alternating current parameters to adjust the phase, displacement and operating frequency of the phase modulation piston, realizes an active phase modulation function, has adjustable size, weight, phase modulation connecting tube length and diameter size, obtains the optimal phase angle of pressure waves and mass flow at the hot end of a pulse tube through matching and adjustment of all parameters, improves the efficiency, realizes the high efficiency of the whole machine, and solves the problems of insufficient phase modulation capability, complex structure, low efficiency and the like of the traditional bidirectional air inlet, small-hole air reservoir and the like.

The application adopts the low-frequency active phase modulation mechanism, can recover the sound work of the hot end of the pulse tube while actively modulating the phase, and further improves the efficiency of the whole machine, thereby realizing the GM pulse tube refrigerator with high reliability and high refrigeration efficiency;

The phase modulation mechanism can select a single-piston active phase modulation mechanism or a double-piston opposite active phase modulation mechanism, the phase modulation piston is supported by an air bearing, the abrasion of the piston is reduced, the service life of the whole machine is prolonged, or a mechanical spring is supported, and the like, so that the flexibility of the phase modulation mechanism is improved.

Drawings

FIG. 1 is a schematic diagram of a single piston active phasing type GM pulse tube refrigerator according to an embodiment 1 of the present utility model;

FIG. 2 is a schematic diagram of a single piston active phasing mechanism according to an embodiment of the utility model;

FIG. 3 is a schematic diagram of an active phase modulation linear motor according to an embodiment of the present utility model;

FIG. 4 is a schematic structural diagram of a dual piston opposed active phasing mechanism according to embodiment 2 of the present utility model;

fig. 5 is a schematic structural diagram of an active phase modulation type two-stage GM pulse tube refrigerator according to embodiment 3 of the present utility model;

Reference numerals illustrate:

1. The device comprises a single-piston active phase modulation mechanism, an active phase modulation linear motor, 1101, an inner stator, 1102, an outer stator, 1103, a coil, 1104, magnetic steel, 12, a phase modulation piston, 13, a cylinder, 14, a framework, 15, a shell, 16 and an end cover;

2. A double-piston opposite active phase modulation mechanism, a 21, an opposite cylinder;

4. A first stage cold finger assembly; 41, a first-stage heat regenerator hot end heat exchanger, 42, a first-stage heat regenerator, 43, a first-stage heat regenerator cold end heat exchanger, 44, a first-stage connecting pipe, 45, a first-stage pulse tube cold end heat exchanger, 46, a first-stage pulse tube, 47, and a first-stage pulse tube hot end heat exchanger;

5. A secondary cold finger assembly; 51, a heat end heat exchanger of a second-stage heat regenerator, 52, a second-stage first-stage heat regenerator, 53, a precooling heat exchanger, 54, a second-stage heat regenerator, 55, a cold end heat exchanger of the second-stage heat regenerator, 56, a second-stage connecting pipe, 57, a cold end heat exchanger of a second-stage pulse tube, 58, a second-stage pulse tube, 59 and a heat end heat exchanger of the second-stage pulse tube;

6. a compressor, 61, a primary helium pipe, 62, a rotary valve, 63, a secondary helium pipe;

10. a first-stage phase modulation connecting pipe;

70. and a second-stage phase modulation connecting pipe.

Detailed Description

For the purpose of making the objects, technical solutions and advantages of the embodiments of the present utility model more apparent, the technical solutions in the embodiments of the present utility model will be clearly and completely described in the following in conjunction with the embodiments of the present utility model, and it is apparent that the described embodiments are some embodiments of the present utility model, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the utility model without making any inventive effort, are intended to be within the scope of the utility model.

Example 1

Referring to fig. 1, an active phase modulation GM pulse tube refrigerator comprises a single-piston active phase modulation mechanism 1, a first-stage cold finger assembly 4, a compressor 6, a first-stage helium pipe 61, a rotary valve 62 and a first-stage phase modulation connecting pipe 10, wherein the compressor 6 is connected with the first-stage cold finger assembly 4 through the first-stage helium pipe 61, the rotary valve 62 is arranged on the first-stage helium pipe 61, and the other end of the first-stage cold finger assembly 4 is connected to the single-piston active phase modulation mechanism 1 through the first-stage phase modulation connecting pipe 10.

Referring to fig. 1 and 2, the single-piston active phase modulation mechanism 1 comprises an active phase modulation linear motor 11, a phase modulation piston 12, a cylinder 13, a framework 14, a shell 15 and an end cover 16, wherein the shell 15 is of a U-shaped structure, the end cover 16 is arranged at the top of the shell, the active phase modulation linear motor 11, the phase modulation piston 12, the cylinder 13 and the framework 14 are integrated in the shell 15, the phase modulation piston 12 is arranged at the middle position of the cylinder 13, the framework 14 is of an inverted U-shaped structure and is arranged above the cylinder 13, the active phase modulation linear motor 11 is positioned at the outer ring of the cylinder 13, the framework 14 is inserted between the active phase modulation linear motor 11 and the cylinder 13, one end of the cylinder 13 in the single-piston active phase modulation mechanism 1 is connected with a primary pulse tube heat exchanger 47 of the primary cold finger assembly 4 through a primary phase modulation connecting tube 10, the phase modulation piston 12 can be supported by springs (column springs or plate springs and the like), the radial direction can be mechanically connected, or can be supported by adopting air bearings, so that piston abrasion is reduced, and the service life of the whole machine is prolonged.

Referring to fig. 2 and 3, the active phase modulation linear motor 11 includes an inner stator 1101, an outer stator 1102, a coil 1103 and magnetic steel 1104, wherein the magnetic steel 1104 is adhered to a frame 14, the frame 14 is fixedly connected with the top of a phase modulation piston 12, the inner stator 1101 is fixed on the outer circle of a thin wall of a cylinder 13, and the outer stator 1102 is sleeved on the coil 1103 and then fixed on the flange end face of the cylinder 13. When the phase modulation device is used, low-frequency alternating current is input to a coil 1103 to form an alternating magnetic field, magnetic steel 1104 drives a phase modulation piston 12 connected with the coil to axially reciprocate under the action of alternating magnetic field force, the phase modulation piston 12 reciprocates in a cylinder 13 to form pressure waves, the phase angle of pulse tube hot end mass flow and the pressure waves is adjusted, the phase, displacement and operating frequency of the phase modulation piston 12 are controlled by changing parameters such as voltage, phase and frequency of a linear motor, so that the optimal phase angle of pulse tube hot end mass flow and the pressure waves is obtained, the optimal active phase modulation function is realized, the hot end sound work is recovered, and the efficiency of the whole device is improved.

Referring to fig. 1, the primary cold finger assembly 4 comprises a primary regenerator hot end heat exchanger 41, a primary regenerator 42, a primary regenerator cold end heat exchanger 43, a primary connecting pipe 44, a primary pulse tube cold end heat exchanger 45, a primary pulse tube 46 and a primary pulse tube hot end heat exchanger 47 which are sequentially connected, wherein the primary regenerator hot end heat exchanger 41 is connected with a primary helium pipe 61, the primary pulse tube hot end heat exchanger 47 is connected with a primary phase modulation connecting pipe 10, gas flows back and forth between the components, cold storage materials are filled in the primary regenerator 42, the cold storage materials such as stainless steel wire mesh, hoCu2, er3Ni and the like are selected to be filled according to different refrigeration temperature areas, and the gas expands in the primary pulse tube 46 to do work and refrigerate.

The compressor 6 supplies air and inputs work to the first-stage cold finger assembly 4, the input work forms high-temperature and high-pressure gas, and the gas is cooled through the first-stage heat regenerator 42 in the first-stage cold finger assembly 4, and expands and absorbs heat at the cold end heat exchanger 43 of the first-stage heat regenerator to absorb external heat so as to achieve a refrigerating effect.

Example 2

Referring to fig. 4, the difference is that the single-piston active phase modulation mechanism 1 in the embodiment 1 is changed into a double-piston opposite active phase modulation mechanism 2, the cylinder 13 in the single-piston active phase modulation mechanism 1 is replaced by an opposite cylinder 21, the active phase modulation linear motor 11, the phase modulation pistons 12 and the frameworks 14 are symmetrically arranged on two sides of the opposite cylinder 21 to form a compression cavity and two back pressure cavities, the compression cavity is formed between the two phase modulation pistons 12, the back pressure cavities are formed between the two frameworks 14 and the end cover 16, the outer shell 15 is in a format with left and right open ends, the end cover 16 is fixed on two ends, the working principle of the double-piston opposite active phase modulation mechanism 2 is the same as that of the single-piston active phase modulation mechanism 1, the two groups of phase modulation pistons 12 can be driven to work simultaneously, and the two opposite phase modulation pistons 12 on two sides carry out low frequency synchronous opposite reciprocating motions under the action of alternating current through inputting the same low frequency alternating current to the two-side active phase modulation linear motor 11, so that the active phase modulation and the recovery of sound work is reduced.

Example 3

Referring to fig. 5, the present example is an active phase modulation type two-stage GM pulse tube refrigerator, i.e. based on the embodiment 2, two groups of double-piston opposite active phase modulation mechanisms 2 are arranged, and a two-stage cold finger assembly 5 is added;

The active phase modulation type two-stage GM pulse tube refrigerator comprises a compressor 6, a rotary valve 62, a first helium tube 61, a second helium tube 63, a first cold finger assembly 4, a second cold finger assembly 5 and two groups of double-piston opposite active phase modulation mechanisms 2, wherein the first cold finger assembly 4 has the same structure as that of the embodiment 1, the embodiment is not repeated, the second cold finger assembly 5 comprises a second heat regenerator hot end heat exchanger 51, a second first heat regenerator 52, a precooling heat exchanger 53, a second heat regenerator 54, a second heat regenerator cold end heat exchanger 55, a second connecting tube 56, a second pulse tube cold end heat exchanger 57, a second pulse tube 58 and a second pulse tube heat exchanger 59 which are sequentially connected, the second heat regenerator hot end heat exchanger 51 is connected with the second helium tube 63, and the second heat end heat exchanger 59 is connected with the second phase modulation connecting tube 70. It should be noted that, the precooling heat exchanger 53 is connected to the first-stage regenerator cold-end heat exchanger 43, and the second-stage pulse tube hot-end heat exchanger 59 is connected to the first-stage pulse tube cold-end heat exchanger 45, so as to precool, and lower the second-stage refrigeration temperature.

Referring to fig. 5, the primary cold finger assembly 4 is connected with one set of double-piston opposite active phase modulation mechanism 2 through a primary phase modulation connecting pipe 10, the other set of double-piston opposite active phase modulation mechanism 2 is connected with the secondary cold finger assembly 5 through a secondary phase modulation connecting pipe 70, the gas quantity of the double-piston opposite active phase modulation mechanism 2 connected with the secondary phase modulation connecting pipe 70 is small, and the required phase modulation mechanism size is reduced compared with that of the other set of double-piston opposite active phase modulation mechanism 2. By respectively inputting alternating current to the two-stage phase modulation mechanisms and respectively adjusting the phases, the displacements and the operating frequencies of the two groups of phase modulation pistons 12 according to the two-stage adjustment requirements, the optimal phase angles of the two-stage pulse tube hot end mass flow and the pressure wave are respectively obtained, the optimal two-stage phase modulation function is realized, and the two-stage hot end acoustic power is recovered. The phasing piston can be supported by an air bearing or by a mechanical support mode.

Example 4

The difference between the two opposite active phase modulation mechanisms is that the two opposite active phase modulation mechanisms 2 are replaced by a single active phase modulation mechanism 1 (not shown in the figure), the structure of the single active phase modulation mechanism 1 is the same as that of the embodiment 1, and details are not repeated in this embodiment, and in this embodiment, the phase modulation piston 12 can be supported by an air bearing or by a mechanical support mode.

The foregoing embodiments are merely for illustrating the technical solution of the present utility model, but not for limiting the same, and although the present utility model has been described in detail with reference to the foregoing embodiments, it will be understood by those skilled in the art that modifications may be made to the technical solution described in the foregoing embodiments or equivalents may be substituted for parts of the technical features thereof, and that such modifications or substitutions do not depart from the spirit and scope of the technical solution of the embodiments of the present utility model in essence.

Claims (10)

1. The active phase modulation type GM pulse tube refrigerator is characterized by comprising an active phase modulation mechanism, a cold finger assembly, a compressor (6) and a phase modulation connecting tube, wherein the active phase modulation mechanism is connected to the cold finger assembly through the phase modulation connecting tube, the cold finger assembly is connected to the compressor (6) through a helium tube, and a rotary valve (62) is further arranged on the helium tube;

The active phase modulation mechanism comprises a phase modulation piston (12), a framework (14) is connected above the phase modulation piston (12), an active phase modulation linear motor (11) is arranged on the outer side of the framework (14), a cylinder (13) is arranged on the outer side of the phase modulation piston (12), and the active phase modulation linear motor (11) is arranged on the cylinder (13);

The active phasing linear motor (11) drives the phasing piston (12) to axially reciprocate, wherein the phasing piston (12) can reciprocate in the cylinder (13) to form pressure waves.

2. The active phase modulation type GM pulse tube refrigerator according to claim 1, wherein the active phase modulation mechanism comprises a single-piston active phase modulation mechanism (1) and a double-piston opposite active phase modulation mechanism (2);

In the single-piston active phasing mechanism (1), a phasing component formed by the active phasing linear motor (11), the phasing piston (12), the cylinder (13) and the framework (14) is arranged in a shell (15) of the single-piston active phasing mechanism;

In the double-piston opposite active phasing mechanism (2), the cylinder (13) is replaced by an opposite cylinder (21), and phasing components formed by an active phasing linear motor (11), a phasing piston (12) and a framework (14) are symmetrically arranged in a shell (15) of the double-piston opposite active phasing mechanism.

3. An active phase modulation GM pulse tube refrigerator according to claim 2, wherein in the double piston opposite active phase modulation mechanism (2), compression chambers are formed between two sets of said phase modulation assemblies, and back pressure chambers are formed between the outer ends of the two sets of said phase modulation assemblies and the housing (15).

4. The active phase modulation type GM pulse tube refrigerator according to claim 1, wherein the active phase modulation linear motor (11) comprises an inner stator (1101), an outer stator (1102), a coil (1103) and magnetic steel (1104), the magnetic steel (1104) is adhered to a framework (14), the inner stator (1101) is fixed on the thin-wall outer circle of the cylinder (13), and the outer stator (1102) is sleeved on the coil (1103) and fixed on the flange end face of the cylinder (13).

5. The active phase modulation type GM pulse tube refrigerator according to claim 4, wherein a low-frequency alternating current is input to the coil (1103) to form an alternating magnetic field, and the magnetic steel (1104) can drive the phase modulation piston (12) connected with the coil to axially reciprocate under the action of the alternating magnetic field force.

6. The active phase modulation type GM pulse tube refrigerator according to claim 1, wherein the first-stage cold finger assembly (4) is adopted, the first-stage cold finger assembly (4) comprises a first-stage regenerator hot-end heat exchanger (41), a first-stage regenerator (42), a first-stage regenerator cold-end heat exchanger (43), a first-stage connecting tube (44), a first-stage pulse tube cold-end heat exchanger (45), a first-stage pulse tube (46) and a first-stage pulse tube hot-end heat exchanger (47), which are sequentially connected, the first-stage regenerator hot-end heat exchanger (41) is connected with a first-stage helium tube (61), and the first-stage pulse tube hot-end heat exchanger (47) is connected with the phase modulation connecting tube.

7. The GM pulse tube refrigerator according to claim 6, wherein the primary regenerator (42) is filled with a cold storage material.

8. The active phase modulation type GM pulse tube refrigerator according to claim 2, wherein the first-stage cold finger assembly (4) and the second-stage cold finger assembly (5) are used at the same time, the compressor (6) can be connected into the first-stage cold finger assembly (4) and the second-stage cold finger assembly (5) through a first-stage helium pipe (61) and a second-stage helium pipe (63) respectively, and the first-stage cold finger assembly (4) and the second-stage cold finger assembly (5) are connected to corresponding active phase modulation mechanisms through phase modulation connecting pipes.

9. The GM pulse tube refrigerator according to claim 8, wherein the active phase modulation mechanism is a double-piston opposite active phase modulation mechanism (2).

10. The active phase modulation type GM pulse tube refrigerator according to claim 9, wherein the second-stage cold finger assembly (5) comprises a second-stage heat regenerator hot end heat exchanger (51), a second-stage first-stage heat regenerator (52), a precooling heat exchanger (53), a second-stage heat regenerator (54), a second-stage heat regenerator cold end heat exchanger (55), a second connecting tube (56), a second-stage pulse tube cold end heat exchanger (57), a second-stage pulse tube (58) and a second-stage pulse tube hot end heat exchanger (59), which are sequentially connected, wherein the second-stage heat regenerator hot end heat exchanger (51) is connected with a second-stage helium tube (63), and the second-stage pulse tube hot end heat exchanger (59) is connected with the phase modulation connecting tube.