American Magnetics AMI Liquid Helium Level Sensors - Manual

Rev. 1, Nov. 1996
EXCELLENCE IN MAGNETICS AND CRYOGENICS
American Magnetics, Inc.
P.O. Box 2509, 112 Flint Road, Oak Ridge, TN 37831-2509
Phone: (865) 482-1056
Fax: (865) 482-5472
Internet: http://www.americanmagnetics.com
E-Mail: [email protected]
AMI
AMI LIQUID HELIUM LEVEL SENSOR
INSTALLATION, OPERATION, AND
MAINTENANCE INSTRUCTIONS
I. INTRODUCTION
The AMI liquid helium level sensor uses a small Niobium-Titanium (NbTi) wire as the
detector element. A heater creates and helps maintain a normal zone in that portion of
the wire above the liquid helium level while that portion of the wire below the liquid
helium level remains superconducting. The output voltage of the sensor varies linearly
with a change in liquid level.
The AMI liquid helium level sensor is designed to operate with an AMI liquid helium
level meter. Operation of the sensor with other level meters or operation of different
length sensor with a meter calibrated for a specific length may void the sensor
warranty.
II. SPECIFICATIONS
Diameter:. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1/4"
Active lengths:. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 to 80 inches
Overall length: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . usually 1 inch longer than active
length (1/2 inch at top and bottom)
Sensor current: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75 milli-amperes (nominal)
Sensor voltage: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0-60 V DC depending on sensor
length
Nominal sensor resistance:. . . . . . . . . . . . . . . . . . . . 4.5 ohms/cm (11.6 ohms/in.) @ 20K
5.4 ohms/cm (13.7 ohms/in.) @ 300K
Maximum magnetic field: . . . . . . . . . . . . . . . . . . . . . 10 Tesla
Caution symbol: necessary instructions in this document in order to protect
against damage to the product.