Pelletron

rdf:langString Pelletron

rdf:langString A Pelletron is a type of electrostatic generator, structurally similar to a Van de Graaff generator. Pelletrons have been built in many sizes, from small units producing voltages up to 500 kilovolts (kV) and beam energies up to 1 megaelectronvolt (MeV) of kinetic energy, to the largest system, which has reached a DC voltage of over 25 megavolts and produced ion beams with energies over 900 MeV. According to the review paper of F. Hinterberger the pelletron was first developed in the mid 1960s by Prof. Ray Herb. In 1965 Ray together with J. A.Ferr y and T. Pauly founded the National Electrostatics Corporation, to manufacture pelletrons as a solution to the problems of ever larger Van de Graaff machines required at that time for particle physic research. As in the Van de Graaff machine, electric charge is moved by a mechanical transportation system. The charge is carried on a chain of 'pellets' (conductive tubes connected by links made of insulating material), that is used to build up high voltages on the Pelletron terminal. The moving pellets form variable capacitances on which charge is trapped, so as the pellet moves from the charging electrode towards the accumulator and the capacitance to ground reduces, the voltage rises, as charge cannot enter or leave the pellet except at the electrodes.