Helium II level measurement techniques

Celik, D.; Hilton, David K.; Zhang, T; Sciver, S.W. Van

doi:10.1016/s0011-2275(01)00092-3

Cited by 13 publications

(6 citation statements)

References 53 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The detector is a capacitor made up of two concentric cylindrical electrodes. The capacitance changes as rising helium, with dielectric constant = 1.057, fills the space between the electrodes [8,9,10].…”

Section: Helium Level Detectormentioning

confidence: 99%

1 K cryostat with sub-millikelvin stability based on a pulse-tube cryocooler

DeMann¹,

Mueller²,

Field³

2016

Cryogenics

View full text Add to dashboard Cite

A cryogenic system has been designed and tested that reaches a temperature below 1.1 K, with an rms temperature stability of 25 µK. In this system a commercial pulse-tube cryocooler is used to liquify helium gas supplied from an external source. This liquid helium enters a 1 K pot through a large-impedance capillary tube, similar to a conventional 1 K system operated from a liquid helium bath. Unlike a conventional system, however, the molar flow rate of the system can be varied by changing the pressure of the incoming helium. This allows for a trade-off between helium usage and cooling power, which has a maximum value of 27 mW. The measured cooling power and fraction of helium exiting the capillary as liquid agree well with predictions based on an isenthalpic model of helium flow through the capillary. The system is simple to use and inexpensive to operate: The system can be cooled to base temperature in about 3 hours and, with a flow rate giving a cooling power of 13 mW, the helium cost is around $6 per day.

show abstract

Section: Helium Level Detectormentioning

confidence: 99%

1 K cryostat with sub-millikelvin stability based on a pulse-tube cryocooler

DeMann¹,

Mueller²,

Field³

2016

Cryogenics

View full text Add to dashboard Cite

show abstract

“…We focus here on capacitive level gauges [2] which may be parallel plates or concentric cylinders. The principle of operation is simplicity itself: the capacitance is given by…”

Section: Phase Boundary Level Gaugesmentioning

confidence: 99%

Phase boundary detection for dilution refrigerators

Haar

Martin

2004

Review of Scientific Instruments

View full text Add to dashboard Cite

We describe a device to conveniently measure the positions of the phase boundaries in a dilution refrigerator. We show how a simple modification of a standard capacitive level gauge (segmentation of one of the electrodes) permits a direct calibration of the capacitance versus phase boundary position. We compare this direct calibration with the indirect procedure that must be adopted for a conventional capacitive level gauge. The device facilitates the correct adjustment of the 3He/4He fraction in the dilution refrigerator.Comment: 3 page

show abstract

“…The LVDs thus discriminate between liquid level and vapor at discrete intervals rather than continuously. 1 Three LVDs have been used in this work and are located at different heights from the bottom of the cryostat. Since the cryostat was located inside a magnetically shielded room (MSR), there were restrictions on bringing electronic instruments into the vicinity to avoid coupling of parasitic electromagnetic interference to the SQUID sensors.…”

Section: Introductionmentioning

confidence: 99%

Programmable System-on-Chip (PSoC) Embedded Readout Designs for Liquid Helium Level Sensors

Parasakthi¹,

Gireesan²,

Rani³

et al. 2014

SLAS Technology

View full text Add to dashboard Cite

This article reports the development of programmable system-on-chip (PSoC)-based embedded readout designs for liquid helium level sensors using resistive liquid vapor discriminators. The system has been built for the measurement of liquid helium level in a concave-bottomed, helmet-shaped, fiber-reinforced plastic cryostat for magnetoencephalography. This design incorporates three carbon resistors as cost-effective sensors, which are mounted at desired heights inside the cryostat and were used to infer the liquid helium level by measuring their temperature-dependent resistance. Localized electrical heating of the carbon resistors was used to discriminate whether the resistor is immersed in liquid helium or its vapor by exploiting the difference in the heat transfer rates in the two environments. This report describes a single PSoC chip for the design and development of a constant current source to drive the three carbon resistors, a multiplexer to route the sensor outputs to the analog-to-digital converter (ADC), a buffer to avoid loading of the sensors, an ADC for digitizing the data, and a display using liquid crystal display cum light-emitting diode modules. The level sensor readout designed with a single PSoC chip enables cost-effective and reliable measurement system design. Keywords liquid helium level sensor, constant current source, programmable system-on-chip (PSoC), magnetoencephalography (MEG)

show abstract

Helium II level measurement techniques

Cited by 13 publications

References 53 publications

1 K cryostat with sub-millikelvin stability based on a pulse-tube cryocooler

1 K cryostat with sub-millikelvin stability based on a pulse-tube cryocooler

Phase boundary detection for dilution refrigerators

Programmable System-on-Chip (PSoC) Embedded Readout Designs for Liquid Helium Level Sensors

Contact Info

Product

Resources

About