MultipoleField Class Reference

Inheritance diagram for MultipoleField:

Detailed Description

MultipoleField represents one placement of a multipole magnet.


Public Member Functions
	MultipoleField (BLCoordinateTransform &_global2local, BLCMDmultipole *mp)
	constructor.
void	addFieldValue (const G4double point[4], G4double field[6]) const
	addFieldValue() adds the field for this solenoid into field[]. point[] is in global coordinates.
Private Attributes
G4double	fieldRadius
G4double	halflength
G4double	gradient
BLCoordinateTransform	global2local
G4RotationMatrix	rotation
G4double	fringeMaxZ
G4double	fringeDepth
BLEngeFunction	enge
BLCMDmultipole *	mp

Constructor & Destructor Documentation

MultipoleField::MultipoleField	(	BLCoordinateTransform &	_global2local,
		BLCMDmultipole *	mp
	)

constructor.

References BLCMDmultipole::apertureRadius, enge, BLCMDmultipole::fieldLength, fieldRadius, BLCMDmultipole::fringe, fringeDepth, BLCMDmultipole::fringeFactor, fringeMaxZ, BLCoordinateTransform::getGlobal(), BLCoordinateTransform::getRotation(), global2local, halflength, mp, BLCommand::printError(), rotation, BLEngeFunction::set(), and BLElementField::setGlobalPoint().

00324                              : BLElementField(), rotation(), enge(ENGE_QUAD)
00325 {
00326         mp = _mp;
00327         fieldRadius = mp->apertureRadius;
00328         halflength = mp->fieldLength/2.0;
00329         global2local = _global2local;
00330         rotation = global2local.getRotation().inverse();
00331         fringeDepth = mp->fringeFactor * fieldRadius * 2.0;
00332 
00333         // @@@ fringe field not supported
00334         if(mp->fringe != "" && mp->fringe != "0") {
00335                 BLCommand::printError("Invalid fringe value\n");
00336         }
00337         enge.set(0,0,0,0,0,0);
00338         fringeMaxZ = halflength;
00339 
00340         // set global bounding box
00341         G4double local[4], global[4];
00342         local[3] = 0.0;
00343         for(int i=0; i<2; ++i) {
00344                 local[0] = (i==0 ? -1.0 : 1.0) * fieldRadius;
00345                 for(int j=0; j<2; ++j) {
00346                         local[1] = (j==0 ? -1.0 : 1.0) * fieldRadius;
00347                         for(int k=0; k<2; ++k) {
00348                                 local[2] = (k==0 ? -1.0 : 1.0) * fringeMaxZ;
00349                                 global2local.getGlobal(local,global);
00350                                 setGlobalPoint(global);
00351                         }
00352                 }
00353         }
00354 }

Member Function Documentation

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

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

Implements BLElementField.

References B, BLCMDmultipole::decapole, BLCMDmultipole::dipole, BLCMDmultipole::dodecapole, fieldRadius, fringeMaxZ, BLCoordinateTransform::getLocal(), global2local, BLCoordinateTransform::isRotated(), mp, BLCMDmultipole::octopole, BLCMDmultipole::quadrupole, rotation, and BLCMDmultipole::sextupole.

00358 {
00359         G4ThreeVector global(point[0],point[1],point[2]);
00360         G4ThreeVector local;
00361 
00362         global2local.getLocal(local,global);
00363         G4double r = sqrt(local[0]*local[0]+local[1]*local[1]);
00364         if(r > fieldRadius || fabs(local[2]) > fringeMaxZ)
00365                 return;
00366 
00367         G4ThreeVector B(0.0,0.0,0.0);
00368         G4double phi = atan2(local[1],local[0]);
00369 
00370         if(mp->dipole != 0.0) {
00371                 B[1] += mp->dipole;
00372         }
00373         if(mp->quadrupole != 0.0) {
00374                 B[0] += mp->quadrupole * r * sin(phi);
00375                 B[1] += mp->quadrupole * r * cos(phi);
00376         }
00377         if(mp->sextupole != 0.0) {
00378                 B[0] += mp->sextupole * r*r * sin(2.0*phi);
00379                 B[1] += mp->sextupole * r*r * cos(2.0*phi);
00380         }
00381         if(mp->octopole != 0.0) {
00382                 B[0] += mp->octopole * r*r*r * sin(3.0*phi);
00383                 B[1] += mp->octopole * r*r*r * cos(3.0*phi);
00384         }
00385         if(mp->decapole != 0.0) {
00386                 B[0] += mp->decapole * r*r*r*r * sin(4.0*phi);
00387                 B[1] += mp->decapole * r*r*r*r * cos(4.0*phi);
00388         }
00389         if(mp->dodecapole != 0.0) {
00390                 B[0] += mp->dodecapole * r*r*r*r*r * sin(5.0*phi);
00391                 B[1] += mp->dodecapole * r*r*r*r*r * cos(5.0*phi);
00392         }
00393 
00394         if(global2local.isRotated())
00395                 B = rotation * B;
00396 
00397         field[0] += B[0];
00398         field[1] += B[1];
00399         field[2] += B[2];
00400 }