NUCL 55 |
| A directly charge (DC) nuclear cell is a particularly simple and reliable source of high-voltage, low-current pulsed power. Utilization of alpha emitters is desirable in this application since they provide higher energy density and can accumulate to very high voltages. An engineering problem is that the DC cell based on alpha emitters requires an antidynatron mesh and an external power source of mesh voltage. Here we demonstrate use of a beta-DC cell as the source of mesh voltage for the alpha-DC cell. The beta cell was constructed from 24 tritium emitters, 1 Ci activity each, with surface activity of 0.07 Ci/cm2. Aluminum plates were used as beta collector electrodes. Distance between electrodes was optimized to achieve maximum performance. Effect of vacuum, resistance, and capacitance on battery performance was studied. Experimental data on the charging kinetics agree well with results of model projections. This tritium direct charge cell accumulates to Uoc=2500 V and Isc=7 nA. Estimated power output was 4uW, and found to be adequate for electronics bias. The alpha-DC cell was fabricated using a 300 mCi Pu-238 emitter. The emitter was covered with 15u-thick film which improves charge accumulation. Voltage accumulated by the tritium cell achieved 2500 V, and was connected so as to bias the secondary electron rejection mesh. Voltage accumulated by the alpha-DC cell achieved 9 kV. Thus for the first time, a completely autonomous alpha-DC cell was constructed and tested. |
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Radioisotopes for Microbatteries and MEMS
1:30 PM-4:50 PM, Monday, 11 September 2006 Moscone Center -- Room 272, Oral
Division of Nuclear Chemistry & Technology |