Cooling principle

The cooling is performed by means of cryocooler

Cryocooler type: Pulse tube;

Cooling gas: He4;

Pulse tube heat load:

1-st stage: 40 W at 45 K;

2-nd stage: 1 W at 4.2 K;

Minimum temperature: 2.7 K;

Compressor"s power consumption: 10 kW.

Cooler design

To prevent the radiation heat flow from external body of the cryostat to solenoid, the heater is protected by copper shield cooled by the 1-st stage of the pulse tube.

Superconducting solenoid and heat key are cooled by 2-nd stage of the pulse tube by means of copper heat bridges.

To secure high vacuum inside the cryostat body is used the high productivity internal coal pump.

The sample room of the variable-temperature insert is filled by helium gas. The temperature stabilization is performed by temperature controller via PID-regulator using the resistive heater and temperature sensor, located near the sample.

Heat key

Heat key consists of two coaxial copper tubes, connected from one side to the 2-nd stage of the pulse tube, and from other side – to the variable-temperature insert. When the space between tubes is evacuated, the thermal conductivity of the heat key is small, when filled – it is high (for cooling down to 5 K the sample room).

Basic parameters of the system at 8 T

Cryostat height, mm	670
Cryostat diameter, mm	400
Minimum sample temperature, K	1.8
Maximum sample temperature, K	300
Temperature of the 1-st stage, K	30
Operating vacuum, mbar	10-6
Variable-temperature insert diameter, mm	19
Maximum field, T	8
Maximum current, A	90
Field homogeneity, %	1
Solenoid protection	yes
Operation-ready time, hours	< 8
Compressor cooling	water
Helium house length, m	20
Low-frequency electric connectop, pin	4
High-frequency electric connectop, pin	10