外文翻譯--一種新型的測量地熱的半導體溫度計(編輯修改稿)
2025-06-26 08:20 本頁面
【文章內(nèi)容簡介】 photograph) in thermal contact with the transistors is used to protect the transistors from any possible damage when the probe is lowered inside the borehole. The surface equipment consists of a voltage supply from two volt dry cells in series with a sensitive microammeter with adjustable shunts so that it can measure current for temperature variations from 180 C to +100C A twocore cable from the surface equipment is led into the brass tube probe and the cable entry into the probe is made fully watertight by a 0ring seal. Necessary electrical connections have been made inside the probe and extreme care has been taken to ensure that no surface leakage current flows between the cable conductors or transistor leads. The calibration curve illustrating variation of log10i, where i is the current in 181。A through the meter versus temperature (t) in 0C constructed in the laboratory with the help of a temperature bath is shown in figure 2. The calibration curve is practically a straight line and is found to fit the empirical relation i = 34 e It is well known that the performance of a . transistor current amplifier is highly affected by the changes in the ambient temperature. This is mainly due to the shift in the operating point caused by the changes in current gain factor and i0 with temperature. For this, the amplifier cannot be incorporated in the surface equipment which may be subjected to unforeseen temperature fluctuations during operation. To avoid the effect of amplifier drift on the temperature measurement,the amplifying transistor has also been mounted in the persepex block at the probe end and the resultant variation of i which is equal to 2(1 + β) i0 is noted for measurement. For operation, the probe with the cable is lowered inside the borehole upto the required depth and the current indicated by the microammeter in the steady state which is reached in about two minute39。s time, is noted. The temperature under measurement is then deduced from the calibration curve. 3. Conclusion and discussion The present instrument has been specially designed for the study of temperature inside a glacier borehole. The measurement accuracy is dependent on the temperature under measurement. At low temperature (near 20 0 C) when the current i is small, the measurement accuracy is mainly limited by the meter sensitivity. The limitation in accuracy at such low temperature is also due to the fact that the surface leakage current, however small it may be made, bees parable to the saturation current. The instrument designed cart conveniently be used for temperature measurements between — 150 C to + 100 C . Measurement accuracy is about C, C and C when the temperature under measurements is 100 C , O0 C and +50 C respectively. The instrument may be made more sensitive by increasing t
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