Development of space charge measurement system with high positionalal resolution using pulsed electro acoustic method

A positional resolution of space charge measurement system of a pulsed electro acoustic (PEA) method is tried to improve using a newly designed upper electrode unit and a new pulse generator. The improved upper electrode unit with a good terminator contribute to reduce the inductance and it results in reduce a noise. Moreover, in order to apply a pulse voltage to a sample efficiently using a newly adopted pulse generator, the upper electrode diameter was made to be small. In the PEA measurement, we have to take a so-called `reference´ signal, which is used for a deconvolution data processing to get an accurate space charge distribution. In the previous system, we needed to take the reference signal using a thicker sample because the original signal is including a relatively long-tail noise. Therefore, to take the reference using a thinner measurement sample, the noise should be shorter. Since, the above mentioned effort to improve made the resolution higher with the shorter noise, we obtained a charge distribution with the resolution of about 1.6 μm in 25 μm-thick PET film. As the result, a typical measurement result of the space charge distribution in a polyimide film with the thickness of 25 μm was introduced in this report.