Operator's Manual
Issue 14
/
Mar 2016 / UMC0071
Mercury
iPS
©2016 Oxford Instruments NanoScience. All rights reserved.
Page
49
heated to its “normal” i.e. non-superconducting state). For “wet” systems where the magnet is
immersed in a liquid
4
He bath typical switch heater current values are 60 – 65mA. For
cryocooled systems where the magnet is in vaccum typical switch heater current values are 20
– 25mA.
4.4.9 Mode
This parameter is either “Bipolar” or “Unipolar”. In Bipolar mode the power supply group will
ramp in both positive and negative directions up to the current limit specified above. In Unipolar
mode the power supply group will only ramp in the positive direction.
4.4.10 Safety
This parameter specifies the device and signal which will be used to check it is safe to run the
magnet, or if the magnet is already energised will put the power supply group in auto-rundown
mode. Typical values are “None”, MB1.T1, DBx.T1, DBx.L1 or DBx.G1.
None = no safety is applied. The magnet running will not be inhibited.
MB1.T1 or DBx.T1. The magnet temperature is used as a safety threshold for safe
running of the magnet. The threshold value for safe operation is defined by the
“Limit(K)” value (see below). If the magnet temperature signal is coming in via the iPS-
M motherboard temperature sensor circuit then MB1.T1 should be chosen. If the
magnet temperature signal is coming in via a temperature daughter card installed in the
iPS-M then DBx.T1, where x is the slot number the daughter board is installed in, should
be chosen.
DBx.L1. The Helium level is used as a safety threshold for safe running of the magnet.
The threshold value for safe operation is defined by the “Limit(L)” value (see below). As
the signal is coming in via a level meter daughter card installed in the iPS-M then
DBx.L1, where x is the slot number the daughter board is installed in, should be chosen.
DBx.G1. An external signal is used as a safety threshold for safe running of the magnet.
As the signal is coming in via an Auxiliary (labelled Gas flow hence “G1”) daughter card
installed in the iPS-M then DBx.G1, where x is the slot number the daughter board is
installed in, should be chosen. This is primarily for backward compatibility so that
Mercury iPS units can be used with old style ILM2xx series cryogen level meters.
