Optimization and Application of Polarization Voltage Selection Method for ²³⁵U Micro Fission Ionization Chamber

In order to solve the problem that the plateau slope is bigger with a wrong polarization voltage when ²³⁵U micro fission ionization chamber works continuously in different neutron flux measurement channels, this study combines the characteristics that the saturation current of ²³⁵U fission ionization chamber and the initial voltage entering the saturation region increase with the increase of neutron fluence, and performs the plateau curve test in the lowest and highest measurement paths respectively. Based on this, the plateau slope characteristic curves of the ²³⁵U fission ionization chamber in the two measurement channels are established, and the range where the plateau slope changes slightly is defined as the optimal polarization voltage range. The actual polarization voltage is selected by intersecting the optimal polarization voltage range and the actual allowable adjustment range of polarization voltage, so that the plateau slope of all measurement channels between the lowest and highest neutron fluence can be kept at a relatively low level. The practical application proves that the actual polarization voltage selected by the intersection method according to the optimal polarization voltage range is balanced and optimal for all neutron flux level measurement channels.