Liquid Nitrogen Liquid Level Controller

Gamblin, Rodger L.; Goldberg, E.; Scag, D.T.

doi:10.1063/1.1716629

Cited by 2 publications

(1 citation statement)

References 4 publications

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“…A lot of research has been reported on reliable and efficient auto-filling (Landis, Madden, and Goulding 1986;Gamblin, Goldberg, and Scag 1959;Murray and Atkinson 2004;Shuhua Ma et al 2010;Morrell and Manning 1996;Zhao Yiding and Song Zengfeng 2010). Landis et al, Gamblin et al, Murray et al and Morrel et al describes an on-off control method, and Shuhua et al & Zhao et al reports a proportional-integral-derivative (PID) based control method for auto-filling.…”

Section: Introductionmentioning

confidence: 99%

A Low Cost Auto-filling and Refrigeration Rate Regulated Liquid Nitrogen Controller for Near Infrared Instruments

Anugu

Amorim

Garcia

et al. 2018

UPjeng

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Liquid Nitrogen is one of the key refrigerating elements in cooling near infrared science instruments to reduce the dark, readout noises and thermal emissions in the near infrared originated from the instrument structure. Usually, a small liquid nitrogen tank connected to the near infrared instrument is auto filled from a large Dewar in order to maintain required low temperatures during the experiment for several hours. The detectors used in these instruments are quite expensive and they need to be cooled down steadily (< 2K/min) to avoid mechanical damage. The steady state cooling of the detector is the key requirement to be considered while cooling down the detector. In this paper, a controller is developed to auto-fill the liquid nitrogen tank and also to keep the refrigeration rate of the detector below 2K/min. A systematic survey of auto-filling controllers is studied. The auto-filling of liquid nitrogen from Dewar to tank is implemented with a standard on-off controller. To address the critical refrigeration rate of the detector, two approaches are studied: a) by fixed time pumping; b) by feedback the detector cooling rate. In this work we have used inexpensive equipment to develop this controller. It is very successfully used for GRAVITY acquisition camera, a near infrared instrument for European Southern Observatory. This controller has been stable and efficient for our experiment. This low cost controller can be used for any student laboratory and research.

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