Variox integral variable temperature insert and helium reservoir cryostat

The Variox provides a controlled low temperature sample environment, in which the sample is cooled through a static exchange gas. This system offers extremely good temperature control and fast cool down times.

Large 50 mm diameter sample access using standard 4He insert
Wide temperature range from 1.6 to 300 K

Interchangeable inserts available to extend base temperature to 300 mK or 30 mK

3 day hold time
Fast cool down times
Interchangeable tails to suit various applications

Specifications
System components/options
Operation
Applications
Images

Layout and dimensions

Variox integral variable temperature insert and helium reservoir cryostat

Specifications

Temperature range	1.6-300 K using EPS40 pump 3-300 K using GF4 pump
Liquid helium volume	13 litres nominal
Liquid helium consumption at 4.2 K	150 cc/h nominal with sample rod and insert at base temperature
Liquid helium hold time	> 72 hours
Liquid nitrogen volume	9 litres nominal
Liquid nitrogen consumption	300 cc/h nominal
Liquid nitrogen hold time	30 hours
Sample space	50 mm diameter
Temperature stability	+/- 0.1 K using ITC controller, measured over 20 min period
Cooldown time to base temperature	< 60 minutes with LHe bath at 4.2 K and variable temperature insert at 300 K

Tail sets

Each Variox is available with a choice of 5 tail sets for different spectroscopic requirements
Optical tail sets can be fitted with a wide choice of window materials
Custom tails are available for special requirements

Sample rods

A range of sample rods can be supplied with height adjustment, 360° rotation or a goniometer
The sample rod may be fitted with its own thermometer for a more accurate determination of the sample temperature

Sample temperature

The base temperature can be extended to:

300 mK using a HelioxVT insert
30 mK using a KelvinoxVT insert

Pump options

A simple GF4 oil-free vane pump is supplied for operation to approximately 3 K
Lower temperatures require an EPS40 single stage rotary pump

Automation

LabVIEW virtual instruments are available for the ITC503 temperature controller and ILM cryogen level meter to allow automation of temperature and liquid helium level control. These can be integrated into a complete data acquisition system.

The Variox uses an oil-free pump to draw liquid helium from the storage reservoir to a heat exchanger surrounding the central sample tube. Temperature control is achieved by balancing needle valve control of helium flow and power dissipated in an electrical heater, both regulated using an ITC503 temperature controller.

The temperature controlled liquid or gas flows up an annular channel surrounding the sample tube. This contains low pressure helium gas to provide thermal exchange with the sample.

The Variox base temperature of 1.6 K and automated features make it ideal for many applications such as: