TECHNICAL INFORMATION
36
87-900-897-01(C)
PUMP USED IN PRESENCE OF MAGNETIC
FIELDS
Magnetic fields induce eddy currents in the rotor of
a turbomolecular pump that tend to oppose to its
rotation.
The result is increased electrical power consump-
tion by the motor, most of which is dissipated in the
rotor.
Since the rotor is not in contact with the stator the
above power can leave the rotor mainly by radia-
tion and hence the rotor may be overheated while
static parts of the pump remain cool.
This effect is strongly dependant from the intensity,
time function and distribution of the magnetic field.
In general, therefore, an increase in pump current
can be expected.
If this increase is lower than 50% of the current
value drawn by the motor in high vacuum opera-
tion, no particular problem should be expected.
However if the effect is grater, than the case
should be carefully reviewed by Varian's specialist.
As a matter of fact, in case of high magnetic fields,
also important forces might be generated and ap-
plied to the rotor.
ACCESSORIES
DESCRIPTION PART
NUMBER
Inlet screen, ISO 100
969-9302
Inlet screen, ISO 160
969-9304
Heating jacket
969-9818
Water cooling kit for American frac-
tional tubes
969-9337
Water cooling kit for Metric tubes
969-9347
Pump to controller cable
969-9952
Solid state flowmeter 1/4" Swagelock
969-9114
Solid state flowmeter KF16
969-9115
Vibration damper, ISO 100
969-9342
Vibration damper, ISO 160
969-9343
Vent flange NW 10 KF
969-9109
Vent valve with fixed delay time
969-9833
Vent device with adjustable delay time
969-9831
Forepump DS 302, with 1 ph.,
universal motor
949-9325
Forepump MD 60, 120 V
949-9411
Forepump MD 60, 220 V
949-9412
For a complete overview of Varian's extensive
product lines, please refer to the Varian catalog.
