top electrode. The system is enclosed by a pressure vessel filled with insulating gas, such as SF6 (sulfur hexafluoride), and an evacuated beamline. The potential difference between the terminal and ground is used to accelerate several kinds of particles, such as positrons, electrons, and negative and positive ions. Compared to the belt of Van de Graaff generator, the pellet chain can operate at a higher velocity than a rubber belt, without wear creating dust and stoppages, while producing higher voltages and currents. The chain can be charged more uniformly than the belt of a Van de Graaff, so the terminal voltage and therefore particle accelerator energy is more consistent. Large pelletron designs can typically produce a DC Voltage of several tens of MV. Pelletron particle accelerators are used in many fields, including materials analysis, nuclear physics, semiconductor development and production, pharmaceutical research, and in ultra-sensitive mass spectrometers for carbon dating and measurement of other rare isotopes. An electrically identical but mechanically different system is the Laddertron so named because of the physical resemblance to an articulated ladder. References External links Pelletron operation animation at pelletron.com The Pelletron — Max Planck Institute for Metals Research, Stuttgart, Germany (archived link) Pelletron.com — National Electrostatics Corp List of about 240 installed Pelletrons Electrostatic generators Particle accelerators