This is a 6 mega-Volt (MV) electrostatic accelerator of modified NEC1 design. It is a single-ended vertical machine that operates at negative terminal potential and has both accelerator and decelerator tubes. Electrostatic accelerators are often refered to as "van deGraaf Accelerators," the primary difference being NEC's use of pelletron charging chains instead of the old rubber belts and the use of sulfur hexafluoride (SF6) insulating gas.
This accelerator is unique in being designed to operate with a high current recirculating electron beam. Recirculation permits operation at ampere current levels for tens of microseconds despite a charging current four orders of magnitude smaller.
The electrostatic accelerator has a number of significant advantages as an FEL beam source including:
1 National Electrostatics Corp., Middleton, Wisconsin