As described in the manual, three flags, SPAC, WSPAC and PSPAC, which will take space charge into account when do tracking. In my preliminary understanding, SPAC + SELFCOD could calculate space charge based on a cylindrical symmetry chamber, referring to the current center of beam but not orbit given by emit. Meanwhile, "WSPAC" could consider space charge with assuming Gaussian distribution in the all dimensions, corresponding to number of particles in beam (PBUNCH). As for "PSPAC" use the PIC method to decide space charge ( which should be relative to the number of macro-particles?).
However, I truly confuse of "SPAC" on the space charge is simulated according to the number of particles in beam or number of macro-particles?
Many thanks!
PSPAC: Apply space charge effect on particles at SPCH elements defined in the lattice. Please ask Ohmi-san for the usage and parameter settings. Tracking only.
(to be continued)
PSPAC: Apply space charge effect on particles at SPCH elements defined in the lattice. Please ask Ohmi-san for the usage and parameter settings. Tracking only.
SPAC: Apply space charge effect on particles at each DRIFT, extrapolating to nearby other elements. Any distribution of the beam is accepted and a circular beam pipe is assumed. It assumes an electrostatic model and solves Laplace equation at each location. Tracking only.
WSPAC: It assumes 6D Gaussian distribution of the beam, then calculates the space charge force semi analytically. The beam pipe is ignored. Valid for tracking, emittance, and calc/go (either with CALC4D or CALC6D).
See below in the text also.
I have not tested them in recent years with k64, so any issues may be there.
> As described in the manual, three flags, SPAC, WSPAC and PSPAC, which will take space charge into account when do tracking. In my preliminary understanding, SPAC + 'SELFCOD' could calculate space charge based on a cylindrical symmetry chamber, referring to the current center of beam but not orbit given by emit. Meanwhile, "WSPAC" could consider space charge with assuming Gaussian distribution in the all dimensions, corresponding to number of particles in beam (PBUNCH). As for "PSPAC" use the PIC method to decide space charge ( which should be relative to the number of macro-particles?).
Both SPAC and PSPAC use PIC, in different algorithms.
>
> However, I truly confuse of "SPAC" on the space charge is simulated according to the number of particles in beam or number of macro-particles?
SPAC just uses the macro particles currently tracked, whose initial number is given by NPART.
>
> Many thanks!