Tests were conducted to determine what effects temperature might have on the in-core detectors and cables. Detector assemblies 1 and 3 were used for these tests.

4. 5.1 Temperature Effect On Breakdown

The first test was to determine what effect temperature might have on breakdown. For this test, both detector assemblies were placed in an oven and then slowly heated to 700°F. The breakdown was monitored on an oscilloscope connected to the output of the pulse amplifier. Fig­ure 4-5 shows the results of this test. There appears to be no significant change in breakdown voltage over the temperature range tested.

Previous tests indicated that breakdown voltage would decrease as the temperature was raised. However, in these previous tests only part of the detector assembly had been heated, the result being that the density of gas in the heated portion decreased as predicted by the ideal gas law (Equation 4-27):

where

number of gas molecules in whole cable, number of gas molecules in heated section of cable, temperature of heated section of cable, temperature of unheated section of cable, volume of heated section of cable, and volume of unheated section of cable.

A decrease in gas density can also be achieved by lowering the pressure while maintaining constant temperature, and under such conditions it is known that the breakdown voltage decreases Therefore, it seems reasonable that breakdown voltage should decrease when an in-core detector assembly is heated nonuniformly, thus making the two experimental results consistent with each other and with theoretical predictions.

> 600

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«С о

Z 400

О

О

• < ш СИ

со 200

0 100 200 300 403 500 600 700

TEMPERATURE IN °F