Measurement of thermal conductivity of sapphire rods II

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Measurement of thermal conductivity of sapphire rods II

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Measurement of thermal conductivity of sapphire rods II

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Measurement of thermal conductivity of sapphire rodsII

TakafumiUshiba

The university of Tokyo at Hongo

Tsubono Laboratory

KAGRA Cryogenic Payload Meeting

- Purpose of the measurement
- How to measure
- Result
- Discussion
- Summary

KAGRA Cryogenic Payload Meeting

- Final goal
measure the thermal conductivity of Moltech and INPEX sapphire rods with nail head.

- Near goal
measure thermal conductivity of polished Photoran’s sapphire rods near peak temperature to confirm the purity of sapphire rods is well or not.

KAGRA Cryogenic Payload Meeting

Heat bath

- Sample size
diameter :

sample length : 100mm

- One dimensional approximation.
:thermal conductivity

L :length between two temperature sensors,

Q:heat flow,A :sample cross section,

:difference of values of two temperature sensors

temperature

sensor

L

Q

temperature

sensor

heater

KAGRA Cryogenic Payload Meeting

- Sample size
diameter :

sample length : 100mm

- One dimensional approximation.
:thermal conductivity

L :length between two temperature sensor,

Q:heat flow,A :sample cross section,

:difference of values of two temperature sensor

heat bath

temperature

sensor

heater

KAGRA Cryogenic Payload Meeting

This time, I take three data near 30K.

KAGRA Cryogenic Payload Meeting

- Error bars
uncertainty of offset voltage of thermometer

- Peak’s shape
If the offset voltage of thermometer does not depend on temperature, the shape of peak of thermal conductivity is same as the real peak.

KAGRA Cryogenic Payload Meeting

- I measure thermal conductivity near 30K
- The result has too large error bars because of the offset voltage of the temperature sensor.
- In this measurement, I do not confirm the purity of sapphire rod is well or not.
- So, I need to measure thermal conductivity of sapphire rod again near 30K.

KAGRA Cryogenic Payload Meeting