Electric field characteristics of a 400 kV electrostatic energy analyzer

Summary form only given. A 400-kV Proca-Green-type parallel-plate energy analyzer is under development for the 2-MeV Heavy Ion Beam Probe on TEXT-Upgrade. Rather than using guard ring electrodes to maintain a nearly uniform electric field in the analyzer, the design utilizes a shaped top plate to minimize the aberrations in the uniform field region. One consequence of this design is that the electric field structure of the analyzer is somewhat perturbed by the boundary condition imposed due to a grounded vacuum vessel housing the device. In order to quantify this effect, a finite-element simulation has been performed, from which a unique vacuum vessel shape has been developed. The distinctive configuration, in which the parallel-plate energy analyzer is an integral part of the vacuum vessel, complements the analyzer´s shaped top plate, resulting in an extremely uniform field region. The device has dimensions of 96 in×46 in×30 in, giving a uniform field region of 60 in×16 in×8 in, and utilizes a 20-kV/cm electric field with an error in uniformity of less than 1%. In order to evaluate the validity of the finite-element model, a one-quarter-scale device has been built and tested