Hello everyone. I am trying to use a Faraday cup constructed by myself to measure the electrostatic charge presence in particles of a fluidized bed reactor. I am trying to test if it works properly but I am having some problems. I am tried to apply a voltage of 1.5 V till I obtain that voltage between the layers of the cup and then disconnecting it to see if it maintains that potential during some time, but when I disconnect the voltage source it looses the potential in like 2 seconds. Shouldn't it conserve the potential like a capacitor? I have tried to measure the charge of particles connecting the faraday cup to a picoammeter, but when I collect the particles inside I obtain oscillations over and under the zero. Maybe it is not correctly constructed or I am testing it wrong. Thank you so much for your attention. Regards!