PillboxField Class Reference

Inheritance diagram for PillboxField:

BLElementField BLManager::SteppingAction

List of all members.


Detailed Description

PillboxField represents one placement of a pillbox.

frequency=0.0 is accepted and yields a pillbox with a constant Ez = maxGradient (useful to verify units are correct).

Public Member Functions

 PillboxField (G4String &_name, BLCoordinateTransform &_global2local, BLCMDpillbox *_pillbox, G4VPhysicalVolume *_timingPV)
 constructor. _zmin/max are global coordinates.
G4String getName ()
 getName() returns the name of this placement.
void addFieldValue (const G4double point[4], G4double field[6]) const
 addFieldValue() adds the field for this pillbox into field[]. point[] is in global coordinates.
void UserSteppingAction (const G4Step *step)
 doStep() handles a step of the tune particle.

Private Attributes

G4String name
BLCMDpillboxpillbox
G4VPhysicalVolume * timingPV
BLCoordinateTransform global2local
G4RotationMatrix * rotation
G4double timeOffset
G4Track saveTrack
G4int timeCount
G4bool validSaveTrack
G4bool settingTiming
BLFieldMapfieldMap

Friends

class BLCMDpillbox


Constructor & Destructor Documentation

PillboxField::PillboxField ( G4String &  _name,
BLCoordinateTransform _global2local,
BLCMDpillbox _pillbox,
G4VPhysicalVolume *  _timingPV 
)

constructor. _zmin/max are global coordinates.

References BLCMDpillbox::fieldMap, fieldMap, BLCMDpillbox::frequency, BLCoordinateTransform::getGlobal(), BLCoordinateTransform::getRotation(), global2local, BLCMDpillbox::innerLength, BLCMDpillbox::innerRadius, BLCoordinateTransform::isRotated(), name, pillbox, rotation, BLElementField::setGlobalPoint(), settingTiming, timeCount, BLCMDpillbox::timeOffset, timeOffset, timingPV, validSaveTrack, and BLCMDpillbox::wallThick.

00570                                                       :
00571                         BLElementField(), BLManager::SteppingAction()
00572 {
00573         name = _name;
00574         pillbox = _pillbox;
00575         timingPV = _timingPV;
00576         global2local = _global2local;
00577         rotation = 0;
00578         timeOffset = pillbox->timeOffset;
00579         timeCount = 0;
00580         validSaveTrack = false;
00581         settingTiming = false;
00582         fieldMap = pillbox->fieldMap;
00583 
00584         if(global2local.isRotated()) {
00585                 rotation = new G4RotationMatrix(global2local.getRotation());
00586                 rotation->invert();
00587         }
00588 
00589         if(pillbox->frequency == 0.0) {
00590                 timeOffset = 0.0;
00591                 settingTiming = false;
00592         }
00593 
00594         // set global bounding box
00595         G4double local[4], global[4];
00596         local[3] = 0.0;
00597         G4double dz = pillbox->innerLength/2.0 + pillbox->wallThick;
00598         for(int i=0; i<2; ++i) {
00599                 local[0] = (i==0 ? -1.0 : 1.0) * pillbox->innerRadius;
00600                 for(int j=0; j<2; ++j) {
00601                         local[1] = (j==0 ? -1.0 : 1.0) * pillbox->innerRadius;
00602                         for(int k=0; k<2; ++k) {
00603                                 local[2] = (k==0 ? -1.0 : 1.0) * dz;
00604                                 global2local.getGlobal(local,global);
00605                                 setGlobalPoint(global);
00606                         }
00607                 }
00608         }
00609 }


Member Function Documentation

G4String PillboxField::getName (  )  [inline]

getName() returns the name of this placement.

References name.

Referenced by UserSteppingAction().

00076 { return name; }

void PillboxField::addFieldValue ( const G4double  point[4],
G4double  field[6] 
) const [virtual]

addFieldValue() adds the field for this pillbox into field[]. point[] is in global coordinates.

Implements BLElementField.

References B, E, BLCMDpillbox::E2Bfactor, fieldMap, BLCMDpillbox::frequency, BLFieldMap::getFieldValue(), BLCoordinateTransform::getLocal(), global2local, BLCMDpillbox::innerLength, BLCMDpillbox::innerRadius, BLCMDpillbox::maxGradient, BLCMDpillbox::omega, pillbox, BLCMDpillbox::rFactor, rotation, BLCMDpillbox::skinDepth, timeOffset, and BLCMDpillbox::wallThick.

00612 {
00613         G4double local[4];
00614         global2local.getLocal(local,point);
00615 
00616         if(fieldMap) {
00617                 G4double myField[6];
00618                 fieldMap->getFieldValue(local,myField,pillbox->maxGradient,
00619                                                         pillbox->maxGradient);
00620                 // frequency == 0.0 means a d.c. electric field
00621                 G4double timeE=1.0, timeB=0.0;
00622                 if(pillbox->frequency != 0) {
00623                         double tArg = pillbox->omega * (point[3] - timeOffset);
00624                         timeE = cos(tArg);
00625                         timeB = sin(tArg);
00626                 }
00627                 if(rotation) {
00628                         G4ThreeVector B(myField[0],myField[1],myField[2]);
00629                         G4ThreeVector E(myField[3],myField[4],myField[5]);
00630                         B = *rotation * B;
00631                         E = *rotation * E;
00632                         field[0] += B[0] * timeB;
00633                         field[1] += B[1] * timeB;
00634                         field[2] += B[2] * timeB;
00635                         field[3] += E[0] * timeE;
00636                         field[4] += E[1] * timeE;
00637                         field[5] += E[2] * timeE;
00638                 } else {
00639                         field[0] += myField[0] * timeB;
00640                         field[1] += myField[1] * timeB;
00641                         field[2] += myField[2] * timeB;
00642                         field[3] += myField[3] * timeE;
00643                         field[4] += myField[4] * timeE;
00644                         field[5] += myField[5] * timeE;
00645                 }
00646                 return;
00647         }
00648 
00649         G4double x = local[0];
00650         G4double y = local[1];
00651         G4double z = local[2];
00652         G4double r = sqrt(x*x + y*y);
00653         G4double dz = pillbox->innerLength/2.0 + pillbox->wallThick;
00654         if(z < -dz || z > dz || r > pillbox->innerRadius) return;
00655 
00656         // frequency == 0.0 means a d.c. electric field
00657         if(pillbox->frequency == 0.0) {
00658                 // zmin and zmax include the walls, so re-test z position
00659                 if(z >= -pillbox->innerLength/2.0 && 
00660                    z <=  pillbox->innerLength/2.0)
00661                         field[5] += pillbox->maxGradient;
00662                 return;
00663         }
00664 
00665         // compute normal RF pillbox field
00666         double arg = pillbox->rFactor*r;
00667         if(fabs(arg) < 1.0e-20) arg = 0.0;
00668         double j0 = gsl_sf_bessel_J0(arg);
00669         double j1 = gsl_sf_bessel_J1(arg);
00670         double tArg = pillbox->omega * (point[3] - timeOffset);
00671         double ez = pillbox->maxGradient * j0 * cos(tArg);
00672         double bphi = -pillbox->maxGradient*pillbox->E2Bfactor*j1*sin(tArg);
00673         // handle skin depth if in wall or window
00674         double f = 1.0;
00675         if(z > pillbox->innerLength/2.0)
00676                 f=exp(-(z-pillbox->innerLength/2.0)/pillbox->skinDepth);
00677         else if(z < -pillbox->innerLength/2.0)
00678                 f=exp(-(-z-pillbox->innerLength/2.0)/pillbox->skinDepth);
00679         double phi = atan2(point[1],point[0]);
00680         if(rotation) {
00681                 G4ThreeVector B(-bphi*sin(phi)*f, bphi*cos(phi)*f, 0.0);
00682                 G4ThreeVector E(0.0, 0.0, ez*f);
00683                 B = *rotation * B;
00684                 E = *rotation * E;
00685                 field[0] += B[0];
00686                 field[1] += B[1];
00687                 field[2] += B[2];
00688                 field[3] += E[0];
00689                 field[4] += E[1];
00690                 field[5] += E[2];
00691         } else {
00692                 field[0] += -bphi * sin(phi) * f;
00693                 field[1] += bphi * cos(phi) * f;
00694                 field[5] += ez * f;
00695         }
00696 }

void PillboxField::UserSteppingAction ( const G4Step *  step  )  [virtual]

doStep() handles a step of the tune particle.

Implements BLManager::SteppingAction.

References BLCMDpillbox::frequency, getName(), BLManager::getObject(), BLManager::getSteppingManager(), BLCMDpillbox::innerLength, ITERATION_LIMIT, BLCMDpillbox::maxGradient, BLCMDpillbox::omega, BLCMDpillbox::phaseAcc, pillbox, saveTrack, settingTiming, timeCount, BLCMDpillbox::timeIncrement, timeOffset, timingPV, BLCMDpillbox::timingTolerance, and validSaveTrack.

00700 {
00701     // do nothing if d.c. or no field
00702     if(pillbox->frequency <= 0.0 || pillbox->maxGradient == 0.0) return;
00703 
00704     G4Track *track = step->GetTrack();
00705     G4StepPoint *prePoint = step->GetPreStepPoint();
00706     if(!prePoint) return;
00707     G4VPhysicalVolume *prePV = prePoint->GetPhysicalVolume();
00708     G4StepPoint *postPoint = step->GetPostStepPoint();
00709     if(!postPoint) return;
00710     G4VPhysicalVolume *postPV = postPoint->GetPhysicalVolume();
00711     G4SteppingManager *steppingMgr =
00712                                 BLManager::getObject()->getSteppingManager();
00713 
00714     if(prePV == postPV) return;     // neither entering nor leaving
00715 
00716     if(postPV == timingPV) {        // entering timingPV
00717         // save track for setting timeOffset (and tuning if this is first)
00718         saveTrack.CopyTrackInfo(*step->GetTrack());
00719         saveTrack.SetUserInformation(0);
00720         validSaveTrack = true;
00721         // estimate timingOffset by neglecting acceleration
00722         if(!settingTiming) {
00723             settingTiming = true;
00724             double v = saveTrack.GetVelocity();
00725             double dist = pillbox->innerLength/2.0;
00726             double arrival = saveTrack.GetGlobalTime() + dist/v;
00727             // pi/2 because E is a cos() and we want phaseAcc=0
00728             // to be the rising zero-crossing
00729             timeOffset = arrival -
00730                 (pillbox->phaseAcc-pi/2.0)/pillbox->omega;
00731         }
00732     } else if(prePV == timingPV) {          // leaving timingPV
00733         if(++timeCount > ITERATION_LIMIT)
00734                 G4Exception("pillbox","Iteration Limit",FatalException,"");
00735         // check timing offset
00736         double t = track->GetGlobalTime();
00737         double phase = pillbox->omega * (t-timeOffset) + pi/2.0;
00738         double dt = (phase-pillbox->phaseAcc)/pillbox->omega;
00739         timeOffset = timeOffset + dt;
00740         if(fabs(dt) <= pillbox->timingTolerance) {
00741             // Success!
00742             printf("pillbox %s: Time OK  timeOffset=%.4f ns, incremented to "
00743                 "%.4f ns\n",getName().c_str(),timeOffset,
00744                                         timeOffset+pillbox->timeIncrement);
00745             timeOffset += pillbox->timeIncrement;
00746             settingTiming = false;
00747             return;
00748         }
00749         // restore saved data (i.e. jump back to when the track 
00750         // enteered TimingVol)
00751         if(!validSaveTrack)
00752                 G4Exception("pillbox","Invalid Step",FatalException,"");
00753         steppingMgr->GetSecondary()->push_back(new G4Track(saveTrack));
00754         track->SetTrackStatus(fStopAndKill);
00755     }
00756 }


Friends And Related Function Documentation

friend class BLCMDpillbox [friend]


Member Data Documentation

G4String PillboxField::name [private]

Referenced by getName(), and PillboxField().

G4VPhysicalVolume* PillboxField::timingPV [private]

G4RotationMatrix* PillboxField::rotation [private]

Referenced by addFieldValue(), and PillboxField().

G4double PillboxField::timeOffset [private]

G4Track PillboxField::saveTrack [private]

Referenced by UserSteppingAction().

G4int PillboxField::timeCount [private]

Referenced by PillboxField(), and UserSteppingAction().

G4bool PillboxField::validSaveTrack [private]

Referenced by PillboxField(), and UserSteppingAction().

G4bool PillboxField::settingTiming [private]

Referenced by PillboxField(), and UserSteppingAction().

Referenced by addFieldValue(), and PillboxField().


The documentation for this class was generated from the following file:
g4beamline