| Summary: | 碩士 === 國立成功大學 === 太空與電漿科學研究所 === 105 === A rust remover was built using a small pulsed-power system. It is very important since there are a lot of iron products that exist in our daily life. A common problem of all iron tools is that they rust. The rust remover we built is to remove rust using the skin effect of a short pulse current propagating through rusted metal surface. To provide a high current, a small pulsed-power system using two 40 nF capacitors connected in series charged to ~ ± 8 kV storing 2.56 J of total energy was built. A controlled spark gap that can hold up to 16kV voltage was built. To trigger the spark gap, a high voltage trigger pulse generator providing a -18 kV trigger pulse with 55.0 ± 0.4 μs rise time was built by using an ignition coil for cars. In this small pulsed-power system, the rise time of the current (quarter period), the calculated skin depth of iron, and the peak current are 5.2 ± 0.2 μs, 0.4 um and 15.9 ± 0.6 kA, respectively, with an fitted inductance of 212 ± 85 nH and fitted resistance of 1.00± 0.04 Ω. The oscillation frequency is (4.9 ± 0.1) x 106 sec-1. The averaged power of our pulsed-power system is about 230 kW before the output current is full damped in ~ 11 μs. Rust on an iron surface, ~1.8 cm long and ~1.8 cm wide, were expected to be removed in each discharge. More than 2500 shots on the same rusted object were conducted. Unfortunately, the result didn’t meet our expectation and no significant amount of rust was removed. The most possible reason is that the energy was released not only on the rusted surface but also on any (metal) surface along the current path. However, it shows that we don’t need to worry about the erosion on the cables in a pulsed-power system which will be built as the long term goal in our lab.
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