libbpm: bpmsimulation/get_mode_amplitude.c Source File

00001 
00006 #include <bpm/bpm_simulation.h>
00007 #include <math.h>
00008 
00009 complex_t get_mode_amplitude( bpmconf_t *bpm, bpmmode_t *mode, beamconf_t *beam ) {
00010 
00011   double k, L, sigma;
00012   complex_t z;
00013   int idx = ( mode->polarisation == horiz ? 0 : 1);
00014 
00015   if ( mode->order == 0 ) {
00016     // monopole mode, sensititvity in Volt/C
00017     z.re = mode->sensitivity * beam->charge;
00018     z.im = 0.;
00019 
00020   } else if ( mode->order == 1 ) {
00021     // dipole mode, sensitivity in Volt/m/C
00022     // need to include the bunch length effects properly!!!
00023     z.re = mode->sensitivity * beam->bpmhit[idx] * beam->charge;
00024 
00025     // calulcate :
00026     // beam->bunchlength, bpm->cav_length, beam->bpmslope[idx] + beam->bpmtilt[idx]
00027     k = 2*PI / cLight * mode->frequency;
00028     L = bpm->cav_length;
00029     sigma = beam->bunchlength;
00030 
00031     z.im = mode->sensitivity * beam->charge * 
00032            // the slope term
00033            ( 1/k * ( 1 - (k*L/2) / sin (k*L/2) ) * beam->bpmslope[idx]
00034            // the tilt term
00035            + 2 * sigma * sin (k*sigma/2) ); 
00036 
00037   } else if (mode->order == 2 ) {
00038     // quadrupole mode
00039     z.re = 0.;
00040     z.im = 0.;
00041     bpm_warning( "Quadrupole modes are not implemented yet in libbpm...", __FILE__, __LINE__ );
00042 
00043   } else {
00044     bpm_warning( "HOM (O(>2) modes are not implemented yet in libbpm...", __FILE__, __LINE__ );
00045 
00046   }
00047 
00048   return z;
00049 }