外文翻譯--一種新型的測量地?zé)岬陌雽?dǎo)體溫度計(jì)-全文預(yù)覽
【正文】 anges in cable and other bridge arm resistances. The design and construction of the equipment described in this paper was under taken for the use of a glacier expedition party of the Geological Survey of India to study temperature variations with depth inside boreholes in glacier. Obviously, the equipment to suit the purpose should be light and simple in construction, and its performance should not be susceptible to adverse surface climatic variations likely to be encountered. 2. Description The working principle of the instrument is as follows: The current (I) flowing through a PN junction is given by the relation I ≈ i0 (e V/VT 1), (1) 1) Geophysics Division, Geological Survey of India, Calcutta16 (India). This paper is published by the kind permission of the Director General, Geological Survey of India. 2) Numbers in brackets refer to References, page 126. Where io = junction saturation current, V = applied junction voltage which is + ve in the forward direction, VT = Junction barrier voltage = (K T)/q, K = Boltzman constant, T = Junction temperature in 0 K q = electronic charge. When the junction applied voltage is in the forward direction (+ ve), the exponential term in equation (1) predominates and as a result the current increases exponent tally with applied voltage. For applied voltage several times larger than VT (VT is about 26 mV at 25 0 C )in the reverse direction, the current bees independent of the applied voltage and practically remains constant at the saturation current level i0 so long as breakdown or avalanche voltage is not exceeded. This saturation current is actually caused by the flow of thermally generated minority carriers in the P and N regions. Therefore, its value is highly dependent on temperature and in actual practice increases exponentially with it. In the instrument designed this highly temperature dependent nature of the saturation current which is practically unaffected by the magnitude of supply voltage has been utilised for the purpose of measurement. The electronic circuit diagram of the instrument is shown in figure 1. Two reverse biased basecollector PN junctions of Germanium transistors are connected in parallel so that individual saturation currents of the two junctions add up. These two transistors in parallel form temperature sensing head and are in thermal contact with the borehole fluid. Resultant saturation current is then amplified by a third transistor which acts as a D. C. cur
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