Surface-charge distributions on radiation-charged electrets

The authors present measurements of surface-charge distributions on electrets formed isothermally by applying an external bias to an electret ionization chamber while irradiating with X-rays. Charge distributions were measured with an electrostatic voltmeter probe during the formation of the electret and at various times in the life of the electrets. Electrets were also stored over extended periods to observe charge retention characteristics. It was found that charge uniformity is unaffected by changes in charging bias, but is affected by separation of electrodes, and that charge life is similar to that observed on corona-charged electrets. Results of this study may also prove useful in electret dosimetry