Single stage coldheads
The Coolstar single stage coldheads include the 0/12 and 0/40 models, respectively delivery cooling powers of 12 and 40 W at 77 K. These compact models have the major advantage of being some of the smallest GM heads available, and can thus be installed in systems where space is at a premium. The coldheads function independently of orientation, and can also be used with the smaller of the two Coolstar compressors, thus reducing the power and water-cooling requirements.
The Coolstar coldheads use the Gifford McMahon refrigeration cycle, and are driven by a small, low vibration stepper motor. This design offers the unique advantage that motor speed can be regulated to vary the cycle rate, and hence the cooling speed. The variable speed demonstrated by the coldheads lends itself to optimising the coldhead performance in terms of:
- Fast cool-down times, which are achieved by running the coldhead at boost speed
- Longer service intervals can be achieved by reducing the cycle to the lowest suitable speed after cool-down, meaning the wear on the seals is reduced.
The Coolstar coldheads run in conjunction with the Oxford Cryosystems Cryodrive, which delivers compressed helium for the operation of Coolstar coldheads and pumps.