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Two stage coldheads

Compact variable-speed GM coolers

The Coolstar two stage coldheads comprise the 2/9 and 6/30 models, both delivering base temperatures as low as 10 K. These are some of the smallest GM coldheads available, and can be installed in systems where space is at a premium. Coolstar is the only commercially available range of Gifford-McMahon Cryocoolers offering complete control of the Coldhead speed; by using a variable speed stepper motor and proprietary control software, every cooler in the range can be operated at speeds of 40-90 rpm. 

The Coolstar range of coldheads may be used wherever a compact and variable speed head is desirable, in applications from laboratory cryostats to radio astronomy.

Brochure
Software
Features
  • Prolonged service intervals: Decreased Coldhead speed during low demand periods reduces wear on Coldhead seals.
  • Cooling power control: Varying the cycle rate second-by-second offers complete control for integration into OEM systems.
  • Fast cooldown time: Increased Coldhead speed makes it possible to reach 20 K in as little as 16 minutes.
coldheads
k450
Technical specifications

Coolstar 2/9:

  • Nominal Cooling Power at 20K : 2 W @ 72 rpm, 2.4 W @ 90 rpm
  • Nominal Cooling Power at 77 K : 9 W @ 72 rpm, 11 W @ 90 rpm
  • Base temperature (unloaded): 10K
  • Cooldown time of bare coldhead to 20 K: < 16 minutes

Coolstar 6/30:

  • Nominal Cooling Power at 20K : 6 W @ 72 rpm, 7 W @ 90 rpm
  • Nominal Cooling Power at 77 K : 28 W @ 72 rpm, 30 W @ 90 rpm
  • Base temperature (unloaded): 10K
  • Cooldown time of bare coldhead to 20 K: < 18 minutes

The variable speed stepper motor found in a Coolstar coldhead is controlled through the Cryocontroller in the K450 compressor. There are three control modes – Auto Mode, Serial Mode and PCSP Mode – and these may be changed by the user at any time.

  • Auto Mode is commonly used with Cryopumps and is the simplest of the three modes; the K450 will start automatically when turned on and will command the coldhead stepper motor to run at a high speed for a set amount of time, then a lower speed indefinitely. The default is to run at 90 rpm for 60 minutes, then 60 rpm indefinitely.
  • Serial Mode is designed for control of the K450 through CryoConnector software. In Serial Mode, the K450 will not start until ordered to; the Power LED on the front of the K450 will flash if it is awaiting a command to start. Using Cryoconnector software via a PC connected via a serial line to the K450, allows the user to continuously change the coldhead speed in real time. OEM integration is easily achieved by using Cryoconnector software in Server mode.
  • PCSP (Parallel Command and Status Port) Mode is a specialised mode in which coldhead speeds are controlled using the 15-pin controller connection on the front of the K450. PCSP mode is included to allow backwards compatibility with older devices.

Coolstar 2/9:  278 x 129 x 150 mm, 2.5 kg

Coolstar 6/30: 344 x 155 x 207 mm, 6.1 kg

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Our free software and web portal for remote control, monitoring and logging of your Oxford Cryosystems device.

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