1. Marco Statera NA62 - GTK working group meeting 5-4-2011
GTK gas cooling system
Marco Statera
NA62 - GTK working group meeting

2. From test bench to final design
nitrogen from a bottle cooled by a liquid bath
open system
manual regulation of the flow
FINAL DESIGN
closed circuit of nitrogen
zero boil off
automated regulation of the flow
remote control
GTK working group meeting Marco Statera

3. GTK working group meeting 5-4-2011 Marco Statera
The working principle
cold nitrogen gas from a liquid bath
The liquid bath keeps the temperature constant
(pressure is regulated) and is a gas source
closed circuit: nitrogen gas must be cooled down
A cold head reliquefies the returning nitrogen
the driving force of the flow is the pressure of the vessel
a regulating valve controls the flow
GTK working group meeting Marco Statera

4. GTK working group meeting 5-4-2011 Marco Statera
Configuration
One bath and three cooling lines
PRO CONS
- 1 cryostat crosstalking of the flows
- length of the lines (≈20 m)
Three separate baths and cooling lines
- independent cooling flow control - more spare parts
- shorter lines (5 m)
- flexible configuration
GTK working group meeting Marco Statera

5. Scheme of the zero boiling off system
READ
GTK temperature,
liquid level
dewar pressure
coldhead temperature
CONTROL
regulating valve motor
gas output valve (ON/OFF)
coldhead heating
OPTIONAL
GTK in/out gas temperature
flow meter
GTK working group meeting Marco Statera

6. Thermal balance LH coolpower 140T one stage 140W@80K
SOURCE
HEAT LOAD - W
cryostat 30
4 feedtrhough 40
1 regulating valve 10
10 meters line (NEXANS) 5 GT
TOTAL
125
LH coolpower 140T
one stage
lower temperature <15 K
cooldown time to 20 K <55 min
LH 120T
GTK working group meeting Marco Statera

7. Control and interlock concept
The control and interlock must be HW:
LabView stand alone or user friendly PLC
normal operation
different logic for different status: i.e. standby - GTK on – etc
keep the dewar pressure and control the flow by the regulating valve
regulate the GTK temperature
avoid too low temperature
avoid thermal shocks
emergency
the interlock sets an allarm
the gas can be warmed by turning off the cold head and turning on the heater
the system still controls the regulating valve
At the end of the emergency the normal operation can be recovered. Some nitrogen may be lost, the liquid bath is a reserve of nitrogen.
GTK working group meeting Marco Statera

8. GTK working group meeting 5-4-2011 Marco Statera
Costs
CUSTOM CRYOSTAT
10 K€
COLDHEAD
COMPRESSOR
CABLES (4.5 m)
14 K€
CRYOGENIC LINES (5 m + 5 m)
REGULATING VALVE
4 FEEDTHROUGH
11 k€
LIQUID NITROGEN SENSOR
CONTROLLER
2 K€
OTHER SENSORS AND HEATERS
GUESS
QUOTATION (INFN)
GTK working group meeting Marco Statera

9. GTK working group meeting 5-4-2011 Marco Statera
Conclusions
coolig system defined
three separate systems
closed circuit
zero boil off
control and interlock concept
total costs
40 k€ per system (plus VAT)
total 120 k€ + 40 k€ (spare)
time schedule
cryostat ≈12wks
cryogenic line: 8 wks
Installation: tbd
GTK working group meeting Marco Statera