The OPAL Discussion Forum

[Christof Metzger-Kraus <christof.j.kraus AT gmail.com>]

Dear Philippe,

with EMISSIONMODEL=ASTRA all particles are emitted, it doesn't take into consideration any space charge induced fields at the cathode. The model NONEQUIL does this but I don't know how well it works.

The warning about rebinning can be ignored, as Nicole wrote, Opal doesn't rebin (i.e. put all particles into a single energy bin) while particles are still being emitted. You can delay the moment when the energy bins are deleted with e.g.

OPTION, MINSTEPFORREBIN = 1000;

However from the extract of the input I would assume that you don't use any energy bins at all (NBIN is commented out).

Cheers,

Christof

On Mon, May 31, 2021 at 2:13 PM Philippe Piot <philippe.piot AT gmail.com> wrote:

Dear All,

  I am trying to understand how does the emission work in OPAL Specifically, in my simulation, I emit a Gaussian beam from a cathode with:

    DistFT: DISTRIBUTION, TYPE = GAUSS,
   SIGMAX  = 0.002,
   SIGMAY  = 0.002,
   SIGMAT  = 3.4e-12,
            EMISSIONSTEPS = 500,
   CUTOFFLONG = 3,
   CUTOFFX = 0.5,
   CUTOFFY = 0.5, // CUTOFFR is not implemented/wotking?
            EMITTED = True,        
            EMISSIONMODEL = ASTRA,
            EKIN = 0.55,      
//    NBIN=5,
            WRITETOFILE = True;

   What surprises me is that as I increase the charge I should see the onset of space-charge-induced saturation and not all the particle being emitted anymore. But OPAL does emit all the particles -- ultimately the distribution is extremely disrupted (but not as one would expect from space charge). Am I doing anything wrong above?  

  Also, I noticed, independently of charge (or even with FC_solver=None) I get a warning:

OPAL{0}> *****************************************************

OPAL{0}> Warning: attempted to rebin, but not all distribution
OPAL{0}> particles have been emitted. Rebin failed.
OPAL{0}> *****************************************************
OPAL{0}> *****************************************************
OPAL{0}> Warning: attempted to rebin, but not all distribution
OPAL{0}> particles have been emitted. Rebin failed.
OPAL{0}> *****************************************************

   Thank you,  -- Philippe.