Monte Carlo calculation of neck charging in cathode-ray tubes

The charging of the (insulating) neck glass in cathode-ray tubes (CRT) has been studied with the aid of Monte Carlo calculations. The charging of the inside neck glass is due to primary electrons generated by field emission from electrodes of the electron gun or backscattered from the screen, and to electrons generated by secondary emission processes. The simulations show that the wall potential distribution becomes stationary when the average secondary electron yield per incoming electron is equal to one at all wall positions. The electrons landing on the insulator are then transported along the insulator surface via small "hops" toward a metallized surface, where they are absorbed. Depending on the initial potential distribution and on the material properties, the wall may charge either positively or negatively, which leads to the convergence drift of the electron beams sometimes observed in CRT's.