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 Types

enum  State { TIMING_UNKNOWN, SETTING_TIMING, TIMING_COMPLETE }

Private Attributes

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

Friends

class BLCMDpillbox


Member Enumeration Documentation

enum PillboxField::State [private]

Enumerator:
TIMING_UNKNOWN 
SETTING_TIMING 
TIMING_COMPLETE 


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(), isUndetermined(), BLCMDpillbox::maxGradient, name, pillbox, rotation, BLElementField::setGlobalPoint(), state, timeCount, BLCMDpillbox::timeOffset, timeOffset, TIMING_COMPLETE, TIMING_UNKNOWN, timingPV, validSaveTrack, and BLCMDpillbox::wallThick.

00594                                                       :
00595                         BLElementField(), BLManager::SteppingAction()
00596 {
00597         name = _name;
00598         pillbox = _pillbox;
00599         timingPV = _timingPV;
00600         global2local = _global2local;
00601         rotation = 0;
00602         timeOffset = pillbox->timeOffset;
00603         timeCount = 0;
00604         validSaveTrack = false;
00605         state = TIMING_UNKNOWN;
00606         fieldMap = pillbox->fieldMap;
00607 
00608         if(global2local.isRotated()) {
00609                 rotation = new G4RotationMatrix(global2local.getRotation());
00610                 rotation->invert();
00611         }
00612 
00613         if(pillbox->frequency == 0.0 || pillbox->maxGradient == 0.0)
00614                 timeOffset = 0.0;
00615 
00616         // don't tune timeOffset if it is known
00617         if(!isUndetermined(timeOffset))
00618                 state = TIMING_COMPLETE;
00619 
00620         // set global bounding box
00621         G4double local[4], global[4];
00622         local[3] = 0.0;
00623         G4double dz = pillbox->innerLength/2.0 + pillbox->wallThick;
00624         for(int i=0; i<2; ++i) {
00625                 local[0] = (i==0 ? -1.0 : 1.0) * pillbox->innerRadius;
00626                 for(int j=0; j<2; ++j) {
00627                         local[1] = (j==0 ? -1.0 : 1.0) * pillbox->innerRadius;
00628                         for(int k=0; k<2; ++k) {
00629                                 local[2] = (k==0 ? -1.0 : 1.0) * dz;
00630                                 global2local.getGlobal(local,global);
00631                                 setGlobalPoint(global);
00632                         }
00633                 }
00634         }
00635 }


Member Function Documentation

G4String PillboxField::getName (  )  [inline]

getName() returns the name of this placement.

References name.

Referenced by UserSteppingAction().

00078 { 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.

00638 {
00639         G4double local[4];
00640         global2local.getLocal(local,point);
00641 
00642         if(fieldMap) {
00643                 G4double myField[6];
00644                 fieldMap->getFieldValue(local,myField,pillbox->maxGradient,
00645                                                         pillbox->maxGradient);
00646                 // frequency == 0.0 means a d.c. electric field
00647                 G4double timeE=1.0, timeB=0.0;
00648                 if(pillbox->frequency != 0) {
00649                         double tArg = pillbox->omega * (point[3] - timeOffset);
00650                         timeE = cos(tArg);
00651                         timeB = sin(tArg);
00652                 }
00653                 if(rotation) {
00654                         G4ThreeVector B(myField[0],myField[1],myField[2]);
00655                         G4ThreeVector E(myField[3],myField[4],myField[5]);
00656                         B = *rotation * B;
00657                         E = *rotation * E;
00658                         field[0] += B[0] * timeB;
00659                         field[1] += B[1] * timeB;
00660                         field[2] += B[2] * timeB;
00661                         field[3] += E[0] * timeE;
00662                         field[4] += E[1] * timeE;
00663                         field[5] += E[2] * timeE;
00664                 } else {
00665                         field[0] += myField[0] * timeB;
00666                         field[1] += myField[1] * timeB;
00667                         field[2] += myField[2] * timeB;
00668                         field[3] += myField[3] * timeE;
00669                         field[4] += myField[4] * timeE;
00670                         field[5] += myField[5] * timeE;
00671                 }
00672                 return;
00673         }
00674 
00675         G4double x = local[0];
00676         G4double y = local[1];
00677         G4double z = local[2];
00678         G4double r = sqrt(x*x + y*y);
00679         G4double dz = pillbox->innerLength/2.0 + pillbox->wallThick;
00680         if(z < -dz || z > dz || r > pillbox->innerRadius) return;
00681 
00682         // frequency == 0.0 means a d.c. electric field
00683         if(pillbox->frequency == 0.0) {
00684                 // zmin and zmax include the walls, so re-test z position
00685                 if(z >= -pillbox->innerLength/2.0 && 
00686                    z <=  pillbox->innerLength/2.0)
00687                         field[5] += pillbox->maxGradient;
00688                 return;
00689         }
00690 
00691         // compute normal RF pillbox field
00692         double arg = pillbox->rFactor*r;
00693         if(fabs(arg) < 1.0e-20) arg = 0.0;
00694         double j0 = gsl_sf_bessel_J0(arg);
00695         double j1 = gsl_sf_bessel_J1(arg);
00696         double tArg = pillbox->omega * (point[3] - timeOffset);
00697         double ez = pillbox->maxGradient * j0 * cos(tArg);
00698         double bphi = -pillbox->maxGradient*pillbox->E2Bfactor*j1*sin(tArg);
00699         // handle skin depth if in wall or window
00700         double f = 1.0;
00701         if(z > pillbox->innerLength/2.0)
00702                 f=exp(-(z-pillbox->innerLength/2.0)/pillbox->skinDepth);
00703         else if(z < -pillbox->innerLength/2.0)
00704                 f=exp(-(-z-pillbox->innerLength/2.0)/pillbox->skinDepth);
00705         double phi = atan2(point[1],point[0]);
00706         if(rotation) {
00707                 G4ThreeVector B(-bphi*sin(phi)*f, bphi*cos(phi)*f, 0.0);
00708                 G4ThreeVector E(0.0, 0.0, ez*f);
00709                 B = *rotation * B;
00710                 E = *rotation * E;
00711                 field[0] += B[0];
00712                 field[1] += B[1];
00713                 field[2] += B[2];
00714                 field[3] += E[0];
00715                 field[4] += E[1];
00716                 field[5] += E[2];
00717         } else {
00718                 field[0] += -bphi * sin(phi) * f;
00719                 field[1] += bphi * cos(phi) * f;
00720                 field[5] += ez * f;
00721         }
00722 }

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, SETTING_TIMING, state, timeCount, BLCMDpillbox::timeIncrement, timeOffset, TIMING_COMPLETE, timingPV, BLCMDpillbox::timingTolerance, and validSaveTrack.

00726 {
00727     // do nothing if d.c. or no field or timing is complete
00728     if(pillbox->frequency <= 0.0 || pillbox->maxGradient == 0.0) 
00729         state = TIMING_COMPLETE;
00730     if(state == TIMING_COMPLETE) return;
00731 
00732     G4Track *track = step->GetTrack();
00733     G4StepPoint *prePoint = step->GetPreStepPoint();
00734     if(!prePoint) return;
00735     G4VPhysicalVolume *prePV = prePoint->GetPhysicalVolume();
00736     G4StepPoint *postPoint = step->GetPostStepPoint();
00737     if(!postPoint) return;
00738     G4VPhysicalVolume *postPV = postPoint->GetPhysicalVolume();
00739     G4SteppingManager *steppingMgr =
00740                                 BLManager::getObject()->getSteppingManager();
00741 
00742     if(prePV == postPV) return;     // neither entering nor leaving
00743 
00744     if(postPV == timingPV) {        // entering timingPV
00745         // save track for setting timeOffset
00746         saveTrack.CopyTrackInfo(*step->GetTrack());
00747         saveTrack.SetUserInformation(0);
00748         validSaveTrack = true;
00749         state = SETTING_TIMING;
00750         // estimate timingOffset by neglecting acceleration
00751         double v = saveTrack.GetVelocity();
00752         double dist = pillbox->innerLength/2.0;
00753         double arrival = saveTrack.GetGlobalTime() + dist/v;
00754         // pi/2 because E is a cos() and we want phaseAcc=0
00755         // to be the rising zero-crossing
00756         timeOffset = arrival - (pillbox->phaseAcc-pi/2.0)/pillbox->omega;
00757     } else if(prePV == timingPV) {          // leaving timingPV
00758         if(++timeCount > ITERATION_LIMIT)
00759                 G4Exception("pillbox","Iteration Limit",FatalException,"");
00760         // check timing offset
00761         double t = track->GetGlobalTime();
00762         double phase = pillbox->omega * (t-timeOffset) + pi/2.0;
00763         double dt = (phase-pillbox->phaseAcc)/pillbox->omega;
00764         timeOffset = timeOffset + dt;
00765         if(fabs(dt) <= pillbox->timingTolerance) {
00766             // Success!
00767             printf("pillbox %s: Time OK  timeOffset=%.4f ns, incremented to "
00768                 "%.4f ns\n",getName().c_str(),timeOffset,
00769                                         timeOffset+pillbox->timeIncrement);
00770             timeOffset += pillbox->timeIncrement;
00771             state = TIMING_COMPLETE;
00772             return;
00773         }
00774         // restore saved data (i.e. jump back to when the track 
00775         // enteered TimingVol)
00776         if(!validSaveTrack)
00777                 G4Exception("pillbox","Invalid Step",FatalException,"");
00778         steppingMgr->GetSecondary()->push_back(new G4Track(saveTrack));
00779         track->SetTrackStatus(fStopAndKill);
00780     }
00781 }


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().

Referenced by PillboxField(), and UserSteppingAction().

Referenced by addFieldValue(), and PillboxField().


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