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Variable Temperature Devices

Variable Temperature Devices

Cold Temperature Devices : Cobra & Cryostream

An Oxford Instruments Cobra is capable of cooling and heating capillary samples in the temperature range 100-450 K with no nitrogen dewar. We also possess a Cryostream Series 700 which has the same capabilities but requires a dewar of liquid nitrogen. Both systems are compatible with our robotic sample changing system by mounting on movable stages that move the devices. Both the cobra/cryostream and hot air blower can be mounted on the beamline at the same time to cover a wide temperature range. 

  • temperatures 100-500 K

  • units in kelvin (K)

  • Pb calibrant

  • Default ramp rate: 360K/h

  • Fast cool can be used for cooling below 327 K (cobra must also be below 327 K)

cobra.fast_cool_to(125)

  • Kapton sheath used to minimize ice build-up

High Temperature Device : Hot air blower

Used to heat capillary samples from room temperature up to 1100 K. Temperatures of up to 1200 K can be reached with smaller samples. The blower can be used in conjunction with the robotic system to allow for automated collections.

  • Note that the hot air blower is not particularly stable at low temperatures (below ~80 °C).

  • The units of the hot air blower are in Celsius (°C).

  • A Si/Al2O3 mix is used to calibrate the temperature at sample position.

  • Default ramp rate = as fast as possible.

#USEFUL BLOWER COMMANDS blower.setRamp_rate(0) #this will ramp the blower as quick as possible return_to_temperature=“off” #means that after the scan, the device will cool to 80 °C before turning off. blower.off() blower.setControllerAsynchronous(20)

Scripting Variable Temperature Devices

collect_pe2_X(sf(),600,[100,200,300],comment=“VT”,settle_time=180,return_to_temperature=100)

Useful commands:

X = “blower”, “cobra”, or “cryostream” X.move_to_safe() – moves temperature device to a safe position X.move_to_beam() – moves temperature device to beam position X.setTemperature(200) – sets temperature device to 200 (K or °C) X.convert_required_temperature_to_controller_setpoint() X.setUnits() – switch between K and °C X.setTolerance() – set tolerance for “temperature reached” X.setCalibration_file(‘_____.txt’) *for beamline staff X.use_calibration = True *for beamline staff

Run program

Temperature programs can be designed and run as part of a variable temperature scan to do more complicated ramping.

collect_pe2_X(sf(),15,None,frames=5000,run_program=“RampT(100,5),Hold(600),RampT(300,2),Hold(60),StopAll()”

Example commands:

  • SetT(300) – set temperature to 300 °C or K

  • RampT(400,5) - ramp to 400 C or K at ramp rate of 5 °C or K/min

  • Hold(6) – hold for 6 seconds

  • Off() – stops temperature program, but frames will continue collecting

  • StopAll() – stops everything including the data collection

 

Calibration

Temperature devices must be calibrated before first use on the beamline. Calibrations in S:\Science\I15-1_XPDF\Sample Environment. Output saved in \dls_sw\i15-1\calibrations.

def X_calibration():     X.use_calibration = False     sam = sf("Si-Al2O3",[1,10],"Al2O3Si",2.4,0.5,"fq1.0") #or Pb     collect_pe2(sam,60,frames=1,preSleep=0)     collect_pe2_blower(sam,60,range(100,900,100),frames=1,settle_time=60)