1 / 10

Thermal measurements of TPG and Diamond

Thermal measurements of TPG and Diamond. I. Bonad, R. Bates and F. McEwan. Apparatus. Vacuum tank. Anchor. Aluminium thermal shield. Heater wires. Shield heater. Pt100 wires. Sample heater. Pt100_5. 3. 1. 2. 4. Sample. Heat sink. Plastic insulation supports. Pt100_6.

marygoodman
Télécharger la présentation

Thermal measurements of TPG and Diamond

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Thermal measurements of TPG and Diamond I. Bonad, R. Bates and F. McEwan

  2. Apparatus Vacuum tank Anchor Aluminium thermal shield Heater wires Shield heater Pt100 wires Sample heater Pt100_5 3 1 2 4 Sample Heat sink Plastic insulation supports Pt100_6 Water cooled H2O

  3. Details of the measurement • Radiation reduction • Radiation shield around the sample • Shield temperature maintained at sample temperature • Additional shield around the whole apparatus • Cool outside of vacuum tank to -15C or sample temperature • Insulation around outside of vacuum tank • Conduction reduction • RTD wire 44SWG Manganin tied to the cooling block • Thermally insulating mounts for apparatus • Convection reduction • Vacuum tank, with vacuum at 1x10-5 mbar • Accuracy • 4 wire temperature sensors and heater with 4-wire supply • Careful calibration of RTDs against each other (temperature differences important)

  4. Measurement details • Sample size • Defined by thermal shield size and vacuum tank • Presently : 10 cm x 1 cm x 0.1 cm • Heater power • Max at present 0.5 W, typically 0.1 and 0.2 W • Easy to manage temperatures in the shield and only small changes in sample temperature • Requires accurate temperature measurements (TPG ΔT = 0.5C) • Cooling • Use anti-freeze based chiller : -40oC minimum temperature • Peltier elements to further reduce temperature • Measurement cross-check • Used Cu (99.999% pure) sample of similar dimensions • Measured conductivity to be 380 compared to 385 W/mK

  5. The experiment • Sample and thermal shield clamped to cold block • Copper tower to clamp PT100 wires to cold block • Heaters on sample and shield removed Cooling block Pocofoam under test PT100 with Manganin wire Thermal shield

  6. Reduction of parasitics Cold Block P=0 Sample length P1 T0 ΔT1 Heater ΔT2

  7. Analysis method • Impossible to remove all parasitic heat paths, p, to the sample • For zero intentional power have ΔT1 • Apply power P • Keep central temperature constant T0 • As long as ΔT2 is not much larger than ΔT1 then parasitic effects cancel

  8. Results TPG • Conductivity increases with falling temperature • Conductivity of 1900 W/mK at -30oC • Bend in TPG does not affect conductivity along sample Error analysis points to 6% error in conductivity

  9. Results Diamond • Little change in conductivity with temperature • Conductivity only about 1000 W/mK

  10. Final slide • Measured conductivity of TPG and Diamond • Diamond only 1000 W/mK • Bend in TPG does not appear to reduce conductivity • Happy to continue with irradiated samples

More Related