Lakeshore Learning Materials 622 User Manual

Page 70

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Lake Shore Model 620/622/623/647 Magnet Power Supply User’s Manual

Options & Accessories

6-2

Below are specifications for the Model 6226/6476 Liquid Helium Level and Gaussmeter Input Card:

Liquid Helium Level:

Probe Type: NbTi Superconducting Filament

Sample Period: Fixed at 5 seconds

Number of Inputs: 1 four lead measurement

Maximum Resistance: 428

Nominal Excitation Current: 70 mA

Display Resolution: 1%, 0.1 inch, 0.1 cm

Compliance: 30 V

Electronic Accuracy: 1% of full scale

Input Voltage Resolution: > 1 mV out of 30 volts full scale

Sample Interval: 1 min to 24 hours, continuous, or read on demand

Model 6226 Gaussmeter:
Cryogenic Hall Sensor Type: Lake Shore Model HGCT-3020 (transverse) or Model HGCA-3020 (axial)

Number of Inputs: 1 four lead measurement

Display Resolution: 0.01 kG, 0.001 tesla

Nominal Excitation Current: 100 mA

Electronic Accuracy: 1% of full scale

Probe Magnetic Sensitivity: 0.8 mV/kG ±30%

Nominal Field Range: Nominal ±125 kG (@ 0.8 mV/kG)

Input Voltage Resolution: > 0.01 mV out of 0.1 volts full scale

Sample Interval: Probe excited continuously & read when level is not

Model 6476 Gaussmeter:
Cryogenic Hall Sensor Type: Lake Shore Model MST-410 (transverse) or Model MSA-410 (axial)
Number of Inputs: 1 four lead measurement
Nominal Excitation: 1 mA
Probe Magnetic Sensitivity: 20 mV/mG

±

50%

Nominal Field Range: Nominal

±

20 kG (@ 20 mV/kG)

Input Voltage Resolution: > 0.04 mV out of 0.4 volts full scale
Sample Interval: Probe excited continuously & read when level is not
Display Resolution: 0.01 kG (0.001T)
Electronic Accuracy: 1% of full scale

Contact Lake Shore for details on a variety of Hall Probes and Sensors.

6.2.1

Hall Sensor Mounting Considerations - Models HGCT-3020 and HGCA-3020

The Lake Shore Model HGCT-3020 (Transverse) and Model HGCA-3020 (Axial) Cryogenic Hall Sensors are

four terminal, solid state devices that produce output voltage proportional to the product of the input current,

magnetic flux density, and the sine of the angle between the field vector and the plane of the Hall generator.

The active area of the Model HGCT-3020 Transverse Hall Sensor is approximately 0.04 inch in diameter with

the center indicated by a cross on one face of the package. When the control current is applied with the red

lead positive with respect to the black lead, and the magnetic field is perpendicular into the face of the probe

with the cross on it, the Hall voltage is positive at the blue lead with respect to the yellow lead. A reversal in the

mechanical orientation or in the direction of either the magnetic field or the control current results in a polarity

change of the output voltage.

The active area of the Model HGCA-3020 Axial Hall Sensor is approximately 0.03 inch in diameter in the

center of the face opposite the leads. When the control current is applied with the red lead positive with

respect to the black lead, and the magnetic field is perpendicular into the face of the probe opposite the leads,

the Hall voltage is positive at the blue lead with respect to the yellow lead. Again, a reversal in mechanical

orientation or in the direction of either the magnetic field or control current results in a output voltage polarity

change.

Handle the Hall sensor with care. The ceramic substrate is brittle and very sensitive to bending stress. Mount

the sensor to minimize mechanical strains as the sensor cools. Failure rates approaching 10% occur on initial

cool down with improperly installed sensors (sensors surviving initial cool down generally experience no

problems on subsequent cycles). Avoid applying tension to the leads. Bend the leads at any angle so long as

the bend is at least 0.125 inch away from the substrate connection. Mount the device to a non-flexible, smooth

surface with a coefficient of thermal expansion no greater than a factor of three different from that of the

ceramic substrate (about 7 x 10

-6

in/in per K).

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This manual is related to the following products:

623, 620