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Update beamloading #906

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Update beamloading #906

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77e7d0e
temp storage
Jan 14, 2025
c2be1bc
Add possibility for detuning away from optimum for active cavities
Mar 6, 2025
52c517d
Merge branch 'master' into update_beamloading
Mar 6, 2025
286b5ff
fix matlab build
Mar 6, 2025
52a526d
test matlab
Mar 6, 2025
06e8587
Fix matlab build
Mar 6, 2025
62a655a
fix atmeall
Mar 6, 2025
94af515
Merge branch 'master' into update_beamloading
lcarver Mar 6, 2025
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23 changes: 15 additions & 8 deletions atintegrators/BeamLoadingCavityPass.c
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Original file line number Diff line number Diff line change
Expand Up @@ -30,6 +30,7 @@ struct elem
double Rshunt;
double Beta;
double phis;
double detune_angle;
double *vbunch;
double *vbeam_phasor;
double *vbeam;
Expand Down Expand Up @@ -82,6 +83,7 @@ void BeamLoadingCavityPass(double *r_in,int num_particles,int nbunch,
double *vbeamk = Elem->vbeam;
double *vcavk = Elem->vcav;
double *vgenk = Elem->vgen;
double detune_angle = Elem->detune_angle;
double tot_current=0.0;
int i;
size_t sz = nslice*nbunch*sizeof(double) + num_particles*sizeof(int);
Expand All @@ -103,7 +105,7 @@ void BeamLoadingCavityPass(double *r_in,int num_particles,int nbunch,
psi = vgenk[1];
}
/*Track RF cavity is always done. */
trackRFCavity(r_in,le,vgen/energy,rffreq,harmn,tlag,-psi,nturn,circumference/C0,num_particles);
trackRFCavity(r_in,le,vgen/energy,rffreq,harmn,tlag,-psi+detune_angle,nturn,circumference/C0,num_particles);
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Don't you want detune_angle to have the same sign as psi?

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No. The Vgen[1] is psi, and for a main cavity in electron machines the optimum is at -ve psi, which is -ve detuning in frequency due to the -ve gradient. It is the opposite for harmonic cavities.

I prefer to keep it as an absolute delta, which is the most logical.


/*Only allocate memory if current is > 0*/
if(tot_current>0){
Expand Down Expand Up @@ -139,7 +141,7 @@ void BeamLoadingCavityPass(double *r_in,int num_particles,int nbunch,
}
}
if(cavitymode==1){
update_vgen(vbeamk,vcavk,vgenk,phasegain,voltgain);
update_vgen(vbeamk,vcavk,vgenk,phasegain,voltgain,detune_angle);
}
if(buffersize>0){
write_buffer(vbeamk, vbeam_buffer, 2, buffersize);
Expand Down Expand Up @@ -167,7 +169,7 @@ ExportMode struct elem *trackFunction(const atElem *ElemData,struct elem *Elem,
double *vbeam_buffer;
double *vbunch_buffer;
double *z_cuts;
double Energy, Frequency, TimeLag, Length;
double Energy, Frequency, TimeLag, Length, detune_angle;
double qfactor,rshunt,beta;
double *vbunch;
double *vbeam_phasor;
Expand Down Expand Up @@ -204,7 +206,8 @@ ExportMode struct elem *trackFunction(const atElem *ElemData,struct elem *Elem,
/*optional attributes*/
Energy=atGetOptionalDouble(ElemData,"Energy",Param->energy); check_error();
z_cuts=atGetOptionalDoubleArray(ElemData,"ZCuts"); check_error();

detune_angle=atGetOptionalDouble(ElemData,"detune_angle", 0); check_error();

int dimsth[] = {Param->nbunch*nslice*nturns, 4};
atCheckArrayDims(ElemData,"_turnhistory", 2, dimsth); check_error();
int dimsvb[] = {Param->nbunch, 2};
Expand Down Expand Up @@ -238,6 +241,7 @@ ExportMode struct elem *trackFunction(const atElem *ElemData,struct elem *Elem,
Elem->vgen_buffer = vgen_buffer;
Elem->vbeam_buffer = vbeam_buffer;
Elem->vbunch_buffer = vbunch_buffer;
Elem->detune_angle = detune_angle;
}
energy = atEnergy(Param->energy, Elem->Energy);

Expand Down Expand Up @@ -283,7 +287,7 @@ void mexFunction(int nlhs, mxArray *plhs[], int nrhs, const mxArray *prhs[])
double normfact, phasegain, voltgain;
double *turnhistory;
double *z_cuts;
double Energy, Frequency, TimeLag, Length;
double Energy, Frequency, TimeLag, Length, detune_angle;
double qfactor,rshunt,beta;
double *vbunch;
double *vbeam_phasor;
Expand Down Expand Up @@ -322,7 +326,8 @@ void mexFunction(int nlhs, mxArray *plhs[], int nrhs, const mxArray *prhs[])
/*optional attributes*/
Energy=atGetOptionalDouble(ElemData,"Energy",0.0); check_error();
z_cuts=atGetOptionalDoubleArray(ElemData,"ZCuts"); check_error();

detune_angle=atGetOptionalDouble(ElemData,"detune_angle",0.0); check_error();

Elem = (struct elem*)atMalloc(sizeof(struct elem));
Elem->Length=Length;
Elem->blmode=blmode;
Expand Down Expand Up @@ -350,6 +355,7 @@ void mexFunction(int nlhs, mxArray *plhs[], int nrhs, const mxArray *prhs[])
Elem->vgen_buffer = vgen_buffer;
Elem->vbeam_buffer = vbeam_buffer;
Elem->vbunch_buffer = vbunch_buffer;
Elem->detune_angle = detune_angle;
if (nrhs > 2) atProperties(prhs[2], &Energy, &rest_energy, &charge);

if (mxGetM(prhs[1]) != 6) mexErrMsgIdAndTxt("AT:WrongArg","Second argument must be a 6 x N matrix");
Expand Down Expand Up @@ -390,9 +396,10 @@ void mexFunction(int nlhs, mxArray *plhs[], int nrhs, const mxArray *prhs[])
mxSetCell(plhs[0],23,mxCreateString("_buffersize"));
if(nlhs>1) /* optional fields */
{
plhs[1] = mxCreateCellMatrix(2,1);
plhs[1] = mxCreateCellMatrix(3,1);
mxSetCell(plhs[1],0,mxCreateString("TimeLag"));
mxSetCell(plhs[0],1,mxCreateString("ZCuts"));
mxSetCell(plhs[1],1,mxCreateString("ZCuts"));
mxSetCell(plhs[1],2,mxCreateString("detune_angle"));
}
}
else
Expand Down
4 changes: 2 additions & 2 deletions atintegrators/atimplib.c
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Original file line number Diff line number Diff line change
Expand Up @@ -451,15 +451,15 @@ static void compute_kicks_phasor(int nslice, int nbunch, int nturns, double *tur
};


static void update_vgen(double *vbeam,double *vcav,double *vgen,double voltgain,double phasegain){
static void update_vgen(double *vbeam,double *vcav,double *vgen,double voltgain,double phasegain,double detune_angle){
double vbeamr = vbeam[0]*cos(vbeam[1]);
double vbeami = vbeam[0]*sin(vbeam[1]);
double vcavr = vcav[0]*cos(vcav[1]);
double vcavi = vcav[0]*sin(vcav[1]);
double vgenr = vcavr - vbeamr;
double vgeni = vcavi - vbeami;
double vga = sqrt(vgenr*vgenr+vgeni*vgeni);
double vgp = atan2(vgeni,vgenr)-vcav[1];
double vgp = atan2(vgeni,vgenr)-vcav[1]+detune_angle;
vgen[0] += (vga-vgen[0])*voltgain;
vgen[1] += (vgp-vgen[1])*phasegain;
}
2 changes: 1 addition & 1 deletion atmat/atmexall.m
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Expand Up @@ -149,7 +149,7 @@ function atmexall(varargin)
compile(compargs, pmeth);
catch errcomp
if fail
rethrow(err);
rethrow(errcomp);
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Is this to be fixed in another PR then? Maybe you should start with this?

else
fprintf(2, 'Could not compile %s:\n%s\n', pmeth, errcomp.message);
end
Expand Down
6 changes: 4 additions & 2 deletions pyat/at/collective/beam_loading.py
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Expand Up @@ -154,6 +154,8 @@ def __init__(self, family_name: str, length: float, voltage: float,
cavitymode (CavityMode): Is cavity ACTIVE (default) or PASSIVE
buffersize (int): Size of the history buffer for vbeam, vgen, vbunch
(default 0)
detune_angle: Fixed detuning from optimal tuning angle. [rad]
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Should you describe the sign convention here?

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You may want to add this in the docstring of add_beamloading function as well no?


Returns:
bl_elem (Element): beam loading element
"""
Expand All @@ -165,9 +167,9 @@ def __init__(self, family_name: str, length: float, voltage: float,
raise TypeError('cavitymode has to be an ' +
'instance of CavityMode')
zcuts = kwargs.pop('ZCuts', None)
phil = kwargs.pop('phil', 0)
energy = ring.energy
harmonic_number = numpy.round(frequency*ring.circumference/clight)
self.detune_angle = kwargs.pop('detune_angle', 0)
self.Rshunt = rshunt
self.Qfactor = qfactor
self.NormFact = kwargs.pop('NormFact', 1.0)
Expand Down Expand Up @@ -199,7 +201,7 @@ def __init__(self, family_name: str, length: float, voltage: float,
self._vbeam = numpy.zeros(2)
self._vgen = numpy.zeros(2)
self._vcav = numpy.array([self.Voltage,
numpy.pi/2-self._phis-phil])
numpy.pi/2-self._phis])
self.clear_history(ring=ring)

def is_compatible(self, other):
Expand Down