Package xal.model.alg

Class EnvelopeTracker

java.lang.Object

xal.model.alg.Tracker

xal.model.alg.EnvelopeTrackerBase

xal.model.alg.EnvelopeTracker

All Implemented Interfaces:

Remote, IAlgorithm, IArchive, IContextAware

Direct Known Subclasses:

ElsTracker, EnvelopeTrackerPmq, EnvelopeTrackerPmqDipole

public class EnvelopeTracker
extends EnvelopeTrackerBase

Tracking algorithm for propagating EnvelopeProbe objects.

The EnvelopeProbe's state, which is a CovarianceMatrix object, is propagated using the linear optics portion for any beamline element (IElement exposing object) transfer map. The linear portion is represented as a matrix, thus, the state evolution is accomplished by 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.

A defining feature of this algorithm object is that it uses a static step size when computing space charge kicks. Thus, the step size is bound from above by the lowest energy and greatest envelope excursion cases. The step size cannot be increased (say by an adaptive step sizing algorithm) to exploit reduced space charge effects after acceleration.

NOTES: CKA
· The default step size for space charge calculations is currently 4 mm. This may be overly conservative for most applications. Not only is this situation CPU intensive, but it creates a serious burden on memory resources with the amount of storage required by the probe trajectory object.

Author:

Christopher K. Allen, Craig McChesney

See Also:

• EnvelopeTrackerBase.getStepSize()
• EnvelopeTrackerBase.setStepSize(double)
• BeamEllipsoid
• Tracker
• 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
	EnvelopeTracker()	Creates a new instance of EnvelopeTracker
protected	EnvelopeTracker(String strType, int intVersion, Class<? extends IProbe> clsProbeType)	Creates a new, empty, instance of EnvelopeTracker.
protected	EnvelopeTracker(EnvelopeTracker sourceTracker)	Copy constructor for EnvelopeTracker

Method Summary

Modifier and Type	Method	Description
protected void	advanceState(IProbe ifcProbe, IElement iElem, double dblLen)	Advances the probe state through a subsection of the element with the specified length.
EnvelopeTracker	copy()	Creates a deep copy of EnvelopeTracker
void	doPropagation(IProbe probe, IElement elem)	Propagates the probe through the element.

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

EnvelopeTracker

public EnvelopeTracker()

Creates a new instance of EnvelopeTracker

EnvelopeTracker

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

Creates a new, empty, instance of EnvelopeTracker. This method is a protected constructor meant only for child classes.

Parameters:

strType - string type identifier of algorithm

intVersion - version of algorithm

clsProbeType - class object for probe handled by this algorithm.

EnvelopeTracker

protected EnvelopeTracker(EnvelopeTracker sourceTracker)

Copy constructor for EnvelopeTracker

Parameters:

sourceTracker - Tracker that is being copied

Method Details

copy

public EnvelopeTracker copy()

Creates a deep copy of EnvelopeTracker

doPropagation

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

Propagates the probe through the element.

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

See Also:

• Tracker.validProbe(IProbe)

advanceState

protected void advanceState(IProbe ifcProbe,
 IElement iElem,
 double dblLen)
                     throws ModelException

Advances the probe state through a subsection of the element with the specified length. Applies a space charge kick at the end of the element subsection for any probe having nonzero beam current.

Parameters:

iElem - interface to the beam element

ifcProbe - interface to the probe

dblLen - length of element subsection to advance

Throws:

ModelException - bad element transfer matrix/corrupt probe state