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TEMPERATURE CONTROLLERS FOR CRYOGENIC APPLICATIONS.

Author(s) : PAL A. K.

Type of article: Article

Summary

TWO TYPES OF TEMPERATURE CONTROLLERS HAVE BEEN DEVELOPED. IN FIRST ONE, A WIDE LINE NMR (NUCLEAR MAGNETIC RESONANCE) TEMPERATURE CONTROLLER, A GERMANIUM DIODE IS USED AS TEMPERATURE SENSOR. WHEN THE DIODE TEMPERATURE DROPS BELOW THAT SET ON THE CONTROLLER, AN ELECTROMAGNETIC RELAY OPENS, SWITCHING OFF THE CURRENT PULSE WHICH CONTROLS THE COOLING OF THE SAMPLE. COOLING QUENCHES IMMEDIATELY AND STARTS ONLY WHEN THE TEMPERATURE RISES SUFFICIENTLY TO ACTIVATE THE RELAY. THE SYSTEM HAS AN EXCELLENT LONG TERM STABILITY (BETTER THAN 0.05 K) AND RAPID TEMPERATURE CHANGES CAN BE EFFECTED WHEN REQUIRED. THE SECOND ONE IS AN INEXPENSIVE, EASY TO BUILD SYSTEM, USING MICROCIRCUITS AND CAPABLE OF PROVIDING ACCURATE TEMPERATURE CONTROL TO BETTER THAN 5 MK FOR CONSIDERABLE PERIODS, IN THE TEMPERATURE RANGE 14 K TO 300 K. A SILICON EPITAXIAL PLANAR TRANSISTOR INCORPORATED IN ONE ARM OF A WHEATSTONE BRIDGE IS USED AS TEMPERATURE SENSOR. A VOLTAGE D OF TWO POWER THYRISTORS WHICH CONTROLS THE HEATER CURRENT OF A COMBINED GAS-FLOW AND LIQUID-FLOW TYPE CRYOSTAT. J. V.

Details

  • Original title: TEMPERATURE CONTROLLERS FOR CRYOGENIC APPLICATIONS.
  • Record ID : 1982-0029
  • Languages: English
  • Source: Indian J. Cryog. - vol. 3 - n. 4
  • Publication date: 1978
  • Document available for consultation in the library of the IIR headquarters only.

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