The ultra-compact beryllium filter is cooled down with a 2.7 W @ 80 K cryocooler from Thales Cryogenics which requires a water cooling line. The vessel of the cryostat is pumped dynamically and the cryostat is translated into the neutron beam when needed. A logic process controller (Schneider M251) monitors the water flow rate and temperature, the pressure in the vacuum vessel, the temperature of the Thales microprocesor and the temperature of the beryllium filter.
The graphical user interface of the humain machine interface (Schenider HMI GTO 4310) proposes 4 screens selected from a tab bar:
- Temperature evolution of the beryllium block
- Temperature evolution of the Thales electronics
- Synoptic of the cryostat displaying all parameters
- Logs of all actions and errors since the beginning of its use
At the top of the screens, indicators are permanently displayed to report potential alarms and defaults. Data are collected and stored in a flash memory. The cooling of the filter is automatic.
The setpoint is fixed to 80 K. A reduction of the water cooling flow-rate raises an alarm for a minute (flow-rate < 2 L/min). The controller waits for a recovery of the water cooling line and stops the cooler if the alarm remains active more than a minute. The pressure in the vacuum vessel of the cryostat must be lower than 1e-4 mbar. If it increases, the controller raises an alarm which becomes a default when it measures 5e-4 mbar. Similairly, the temperature of the cooler drive electronics is monitored and should not exceed the room temperature + 20 °C.
Full remote control
Computer control via Ethernet is provided for monitoring all parameters and start or stop the cooling. The communications are based on the Modbus communications protocol which is an industrial standard. We provide a Modbus XOP and routines in a Procedure file for controlling Modbus-TCP devices with Igor Pro.
PLC Registers (Schneider M251 Logic Controller)
|Equipment status — Idle bit||X||40 100.0|
|Equipment status — Running bit||X||40 100.1|
|Equipment status — Local/Remote bit||X||X||40 100.2|
|Equipment status — Fault bit||X||40 100.3|
|Equipment status — Start/Stop bit||X||X||40 100.4|
|NOMAD tolerance range (idle and running status)||X||X||40 102|
|Be temperature - top (K)||X||40 104|
|Be temperature setpoint (K)||X||40 106|
|Be temperature - bottom (K)||X||40 108|
|Cooler supplied voltage (V)||X||40 110|
|Cooler supplied current (A)||X||40 112|
|Cooler drive voltage (V rms)||X||40 114|
|Cooler drive electronics temperature (°C)||X||40 116|
|Pressure in vacuum vessel (hPa)||X||40 118|
|Cooling water flow-rate||X||40 120|
Please find below the release history and some instructions for updating the firmware.
- 1.00 - Initial release