Charge injection in polymeric samples: a new experimental analogic set up

The authors present a highly sensitive experimental setup that allows the analog time-resolved measurement of the trapped charge during AC polarization at high field in a double-needle sample configuration. In the first step, the capacitive charge is exactly compensated in a differential bridge. The polarization component is subsequently eliminated by differentiation between two identical samples. The authors present experimental results concerning low-density polyethylene and polyepoxy samples. The AC threshold fields for charge injection are compared for both materials