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5 years ago

Applying the pulsed ion chamber methodology to full range reactor ...

Applying the pulsed ion chamber methodology to full range reactor ...

in in > h Z ;,t »u iJJ

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To glean information from the data more easily., the leakage current was subtracted from all current values arid the ratio of I /v(t ) was SS ' c computed for all data point:;. Tables 4-2 and 4-3 contain the results for the Ar-Np and Ne chambers, respectively. The blank spaces indicate the result obtained was meaningless. Figures 4-24 and 4-25 present the tabulated I ss /v(t ) ratio at position 3 as a function of temperature for He and Ar-N ? data, respectively. The reason for calculating the ratio was to smooth out fluctuations in the data caused by vertical and rotational positioning differences between data sets. Since I is constant for a given exposure rate, over the temperature range of interest, v(t ) accounts for the variation in the ratio * ss /v(t c ). If v(t c ) gets larger in the second order region, this indicates that the volume recombination coefficient is decreasing. Note, as we'll, that as v(t ) nets larger I. /v(t ) gets smaller. v.. iS c With these facts in mind examine the Ne data in Table 4-2 and Figure 4-24. In particular choose a position where v(t ) is in the second order region, for instance, position 3. The ratio of I /v(t ) changes considerably over the temperature range of interest. At 25°C the ratio for the gamma chamber is 4.36 x 10"° while at 477°C it is 1.32 x 10 . The same temperature range for the fission chamber gives a ratio range of 4.34 x 10"'° to 1.87 x 10 . Note that the relative changes are approximately equal for both chambers. As one will see this is not true for the Ar-N ? chambers. This indicates the a ? decreases with increasing temperature for Ne; a fact which appears to contradict Sanders results. Sanders found u,. constant for No from 25°C to 300°C. L Examining the data given in the lower part of Table 4-2 (positions 1.5, 2.5, 3, 3.5) more closely, one notes that the ratio is virtually constant