Package xal.model.alg

Class EnvelopeBacktracker

java.lang.Object

xal.model.alg.Tracker

xal.model.alg.EnvelopeTrackerBase

xal.model.alg.EnvelopeBacktracker

All Implemented Interfaces:

Remote, IAlgorithm, IArchive, IContextAware

public class EnvelopeBacktracker
extends EnvelopeTrackerBase

Tracking algorithm for EnvelopeProbe objects.

This tracker object is based The EnvelopeProbe's state, which is a CovarianceMatrix object, is advanced using the linear dynamics portion of any beamline element (IElement exposing object) transfer map. The linear portion is represented as a matrix, thus, the state advance is accomplished with a transpose conjugation with this matrix.

The effects of space charge are also included in the dynamics calculations. Space charge effects are also represented with a matrix transpose conjugation, however, the matrix is computed using the values of the probe's correlation matrix. The result is a nonlinear effect. The space charge forces are computed using a linear fit to the fields generated by an ellipsoidal charge distribution with the same statistics described in the probe's correlation matrix. The linear fit is weighted by the beam distribution itself, so it is more accurate in regions of higher charged density. For a complete description see the reference below.

NOTES: (CKA)
· This class has been un-deprecated. Currently refactoring the hierarchy structure of the Algorithm base to simplify implementation of implementation is not supported yet. Considering a modification of the Tracker class

Since:

Feb 4, 2009

Version:

1.0

Author:

Christopher K. Allen

See Also:

• BeamEllipsoid
• EnvelopeTracker
• Theory and Technique of Beam Envelope Simulation

Nested Class Summary

Nested classes/interfaces inherited from class xal.model.alg.EnvelopeTrackerBase

EnvelopeTrackerBase.EmitGrowthModel, EnvelopeTrackerBase.PhasePlane

Field Summary

Fields

Modifier and Type	Field	Description
static final Class<EnvelopeProbe>	CLS_PROBE_TYPE	probe type recognized by this algorithm
static final String	TYPE_ID	string type identifier for algorithm
static final int	VERSION	current algorithm version

Fields inherited from class xal.model.alg.EnvelopeTrackerBase

ATTR_EMITGROWTH, ATTR_SCHEFF, ATTR_STEPSIZE, ATTR_USEDCBEAM, ATTR_USESPACECHARGE, LABEL_OPTIONS, TBL_LBL_ENVBASETRACKER

Fields inherited from class xal.model.alg.Tracker

ATTRTAG_DEBUG, ATTRTAG_RFGAP_PHASE, ATTRTAG_TYPE, ATTRTAG_UPDATE, ATTRTAG_VER, NODETAG_ALG, NODETAG_TRACKER, TBL_LBL_ALGORITHM, TBL_PRIM_KEY_NAME, UPDATE_ALWAYS, UPDATE_CUSTOM, UPDATE_ENTRANCE, UPDATE_ENTRANCEANDEXIT, UPDATE_EXIT

Constructor Summary

Constructors

Modifier	Constructor	Description
	EnvelopeBacktracker()	Create a new, uninitialized EnvelopeBacktracker() algorithm object.
protected	EnvelopeBacktracker(String strType, int intVersion, Class<? extends IProbe> clsProbeType)	This method is a protected constructor meant only for building child classes.
	EnvelopeBacktracker(EnvelopeBacktracker sourceTracker)	Copy constructor for EnvelopeBackTracker

Method Summary

Modifier and Type	Method	Description
EnvelopeBacktracker	copy()	Create a deep copy of EnvelopeBackTracker
void	doPropagation(IProbe probe, IElement elem)	Implementation of Abstract Tracker#doPropagation(IProbe, IElement)
protected void	retractState(IProbe ifcProbe, IElement ifcElem, double dblLen)	Back-propagates the Defining State of the Probe Object

Methods inherited from class xal.model.alg.EnvelopeTrackerBase

compEmitGrowthFunction, compLongFourierTransform, compScheffMatrix, compTransFourierTransform, correctLongSigmaPhaseSpread, correctSigmaPhaseSpread, correctTransFocusingPhaseSpread, correctTransSigmaPhaseSpread, effPhaseSpread, fourierLong1dGaussian, fourierLong1dUniform, fourierLong3dGaussian, fourierLong3dUniform, fourierLongTrace3d, fourierTrans1dGaussian, fourierTrans1dUniform, fourierTrans3dGaussian, fourierTrans3dUniform, fourierTransTrace3d, getEmitGrowthModel, getEmittanceGrowth, getEmittanceGrowthFlag, getSpaceChargeFlag, getStepSize, getUseDCBeam, getUseSpacecharge, load, load, modTransferMatrixForEmitGrowth, phaseSpread, save, setEmitGrowthModel, setEmittanceGrowth, setStepSize, setUseDCBeam, setUseSpacecharge

Methods inherited from class xal.model.alg.Tracker

advanceProbe, getDebugMode, getElemPosition, getProbeType, getProbeUpdatePolicy, getRfGapPhaseCalculation, getStartElementId, getStopElementId, getType, getVersion, initialize, isStopElementIncluded, newFromEditContext, newFromEditContext, newInstance, propagate, registerProbeType, retractProbe, setDebugMode, setElemPosition, setIncludeStopElement, setProbeUpdatePolicy, setRfGapPhaseCalculation, setStartElementId, setStopElementId, unsetStartElementId, unsetStopElementId, validElement, validProbe

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Details

TYPE_ID

public static final String TYPE_ID

string type identifier for algorithm

VERSION

public static final int VERSION

current algorithm version

See Also:

• Constant Field Values

CLS_PROBE_TYPE

public static final Class<EnvelopeProbe> CLS_PROBE_TYPE

probe type recognized by this algorithm

Constructor Details

EnvelopeBacktracker

public EnvelopeBacktracker()

Create a new, uninitialized EnvelopeBacktracker() algorithm object. This is the default constructor to be used when creating objects of this type.

EnvelopeBacktracker

protected EnvelopeBacktracker(String strType,
 int intVersion,
 Class<? extends IProbe> clsProbeType)

This method is a protected constructor meant only for building child classes.

Parameters:

strType - string type identifier of algorithm

intVersion - version of algorithm

clsProbeType - class object for probe handled by this algorithm.

EnvelopeBacktracker

public EnvelopeBacktracker(EnvelopeBacktracker sourceTracker)

Copy constructor for EnvelopeBackTracker

Parameters:

sourceTracker - Tracker that is being copied

Method Details

copy

public EnvelopeBacktracker copy()

Create a deep copy of EnvelopeBackTracker

doPropagation

public void doPropagation(IProbe probe,
 IElement elem)
                   throws ModelException

Implementation of Abstract Tracker#doPropagation(IProbe, IElement)

This method is essentially the same implementation as the method EnvelopeTracker#doPropagation(), only here the probe object is back-propagated. The method calls Tracker.retractProbe() rather than Tracker.advanceProbe(), and the implemented method EnvelopeBacktracker.retractState() rather than EnvelopeTracker.advanceState.

Specified by:

doPropagation in class Tracker

Parameters:

probe - probe to propagate

elem - element acting on probe

Throws:

ModelException - invalid probe type or error in advancing probe

Since:

Feb 9, 2009

See Also:

• Tracker.propagate(xal.model.IProbe, xal.model.IElement)
• EnvelopeTracker.doPropagation(IProbe, IElement)

retractState

protected void retractState(IProbe ifcProbe,
 IElement ifcElem,
 double dblLen)
                     throws ModelException

Back-propagates the Defining State of the Probe Object

This method uses the same basic algorithm as in EnvelopeTracker#advanceState(), only the probe object is back-propagated. The method utilizes all the space charge mechanisms of the base class EnvelopeTracker.

Parameters:

ifcElem - interface to the beam element

ifcProbe - interface to the probe

dblLen - length of element subsection to retract

Throws:

ModelException - bad element transfer matrix/corrupt probe state

Since:

Feb 9, 2009

See Also:

• EnvelopeTracker.advanceState(xal.model.IProbe, xal.model.IElement, double)