Electrostatic Systems

Abstract

This chapter introduces to electrostatic systems used in beam optics, and to the theoretical material needed for the simulation exercises. It begins with a brief reminder of the historical and technological context, and continues with electrostatic optics methods which beam handling, guiding and focusing lean on. optical element library offers analytical modeling of several electrostatic components. For instance ELCYLDEF: an electrostatic deflector; ELMULT: a multipole, up to 20 poles; WIENFILTER: a plane condenser, possibly combining a magnetic dipole; ELMIR, ELMIRC: N-electrode mirrors and condenser lenses, with straight or circular slits. Electrostatic elements can be simulated as well using field maps, via the keywords TOSCA, MAP2D-E or ELREVOL. Running a simulation generates a variety of output files, including the execution listing zgoubi.res, always, and, on demand, such files as zgoubi.plt, zgoubi.fai, zgoubi.MATRIX.out, aimed at looking up program execution, storing data for post-treatment such as graphics, etc. Additional keywords are introduced as needed in the exercises, such as the matching procedures FIT[2]; FAISCEAU and FAISTORE to log local particle data in zgoubi.res or in a user defined ancillary file; MARKER; the ‘system call’ command SYSTEM; REBELOTE do-loop for multiple-pass or for parameter scans; and some more. This chapter introduces in addition to spin motion in electrostatic fields, the simulation of which is triggered by the keywords SPNTRK. SPNPRT or FAISTORE log spin vector components in respectively zgoubi.res or an ancillary file. The “IL = 2” flag logs stepwise particle data, including spin vector, in zgoubi.plt file. Simulations include deriving transport matrix, beam matrix, optical functions, from rays, using MATRIX and TWISS keywords.