Bruker BioSpin Solid State NMR, User Manual

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Additional Connections for VT Operation
User Manual Version 002 BRUKER BIOSPIN 31 (327)
Figure 3.20. SB DVT probe MAS connections.
The numbered connectors are the same as the VTN probe. Connectors 7 and 8
are not present since the probe does not tilt the stator for eject (not required for
2.5 mm probes).
Additional Connections for VT Operation 3.6
If V ariable T emperature experiments must be run, there are a few connections to
be done which are not required for room temperature experiments.
First of all, there must be a flow of VT control gas. For MAS probes, this flow can
be the bearing gas (VTN) or it can be separate (DVT). In any case, the VT control
gas will flow through a dewar which contains a heater. There will be at least one
thermocouple which senses the temperature as close as possible to the sample.
Several requirements must be fulfilled to obtain precise and stable temperature
readings as close as possible to the real sample temperature. This will however
be part of a different chapter.
Some connections are required to control the temperature of the probe/sample,
others are necessary to protect the probe and the magnet from illegal tempera-
tures. MAS probes are usually not as well insulated as for instance a wideline or
PE stationary probe is. Therefore the probe outer shell warms/cools down during
the experiment. The heat transfer between heater and probe electronics/probe
environment must be kept at a safe level.