Package xal.model.elem

Class IdealRfGap

java.lang.Object

xal.model.elem.Element

xal.model.elem.ThinElement

xal.model.elem.IdealRfGap

All Implemented Interfaces:

IRfGap, IComponent, IElement

public class IdealRfGap
extends ThinElement
implements IRfGap

Represents the action of an ideal RF gap. Gap is modeled as a thin element whose accelerating action is given by the Panofsky formula.

The gap provides acceleration to the propagation probe as well as longitudinal focusing and radial defocusing. These mechanisms are implemented according to that provided by an ideal gap where the effects can be described analytically.

Since:

November 22, 2005

Author:

Christopher K. Allen

Field Summary

Fields

Modifier and Type	Field	Description
static final String	PARAM_ETL	Parameters for XAL MODEL LATTICE dtd
static final String	PARAM_FREQ	Description of the Field
static final String	PARAM_PHASE	Description of the Field
static final String	TYPE	the string type identifier for all IdealRfGap objects

Fields inherited from class xal.model.elem.Element

dblNodeLen, dblNodePos

Fields inherited from interface xal.model.IElement

LIGHT_SPEED, PERMEABILITY, PERMITTIVITY, UNIT_CHARGE

Constructor Summary

Constructors

Constructor	Description
IdealRfGap()	JavaBean constructor - creates a new uninitialized instance of IdealRfGap BE CAREFUL
IdealRfGap(String strId, double dblETL, double dblPhase, double dblFreq)	Creates a new instance of IdealRfGap

Method Summary

Modifier and Type	Method	Description
double	betaMidGap(IProbe probe)	Compute and return the mid-gap normalized velocity for the given probe.
double	compLongFocusing(IProbe probe)	Get the longitudinal focusing constant for a particular probe.
double	compTransFocusing(IProbe probe)	Get the transverse focusing constant for a particular probe.
void	computeSynchronousPhaseAndEnergyGain(IProbe probe)	Compute the synchronous phase and the energy gain for a cavity gap.
double	elapsedTime(IProbe probe)	Returns the time taken for the probe to propagate through element.
double	energyGain(IProbe probe)	Compute the energy gain of the RF gap for a probe including the effects of calculating the phase advance.
double	getCellLength()	return the cell length (m)
double	getE0()	Get the on accelerating field (V/m)
double	getEnergyGain()	Return the energy gain of a cavity gap previously calculated.
double	getETL()	Return the ETL product of the gap, where E is the longitudinal electric field, T is the transit time factor, and L is the gap length.
double	getFrequency()	Get the operating frequency of the RF gap.
double	getPhase()	Return the RF phase delay of the gap with respect to the synchronous particle.
double	getSynchronousPhase()	Return the synchronous phase of a cavity gap, which must be previously calculated using computeSynchronousPhase.
void	initializeFrom(LatticeElement element)	Conversion method to be provided by the user
boolean	isFirstCell()	return whether this gap is the initial gap of a cavity
void	print(PrintWriter os)	Dump current state and content to output stream.
void	setE0(double e)	Set the on accelerating field @ param E - the on axis field (V/m)
void	setETL(double dblETL)	Set the ETL product of the RF gap where E is the longitudinal electric field of the gap, T is the transit time factor of the gap, L is the length of the gap.
void	setFrequency(double dblFreq)	Set the operating frequency of the RF gap.
void	setPhase(double dblPhase)	Set the phase delay of the RF in gap with respect to the synchronous particle.
double	simpleEnergyGain(IProbe probe)	Compute the energy gain of the RF gap for a probe assuming a fixed default phase at the gap center.
protected PhaseMap	transferMap(IProbe probe)	Compute the transfer map for an ideal RF gap.
double	wavelengthRF()	Compute the wavelength of the RF.

Methods inherited from class xal.model.elem.ThinElement

applyErrors, elapsedTime, energyGain, getLength, longitudinalPhaseAdvance, longitudinalPhaseAdvance, transferMap

Methods inherited from class xal.model.elem.Element

addCloseElements, backPropagate, backPropagate, compDriftingTime, compProbeLocation, getAlignX, getAlignY, getAlignZ, getCloseElements, getHardwareNodeId, getId, getLatticePosition, getNodeLen, getNodePos, getParent, getPhiX, getPhiY, getPhiZ, getPosition, getType, getUID, propagate, propagate, setAlign, setAlignX, setAlignY, setAlignZ, setHardwareNodeId, setId, setParent, setPhiX, setPhiY, setPhiZ, setPosition, toString

Methods inherited from class java.lang.Object

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

Field Details

TYPE

public static final String TYPE

the string type identifier for all IdealRfGap objects

See Also:

• Constant Field Values

PARAM_ETL

public static final String PARAM_ETL

Parameters for XAL MODEL LATTICE dtd

See Also:

• Constant Field Values

PARAM_PHASE

public static final String PARAM_PHASE

Description of the Field

See Also:

• Constant Field Values

PARAM_FREQ

public static final String PARAM_FREQ

Description of the Field

See Also:

• Constant Field Values

Constructor Details

IdealRfGap

public IdealRfGap(String strId,
 double dblETL,
 double dblPhase,
 double dblFreq)

Creates a new instance of IdealRfGap

Parameters:

strId - instance identifier of element

dblETL - field/transit time/length factor for gap (in volts )

dblPhase - operating phase of gap (in radians )

dblFreq - operating RF frequency of gap (in Hertz )

IdealRfGap

public IdealRfGap()

JavaBean constructor - creates a new uninitialized instance of IdealRfGap BE CAREFUL

Method Details

getETL

public double getETL()

Return the ETL product of the gap, where E is the longitudinal electric field, T is the transit time factor, and L is the gap length.

Specified by:

getETL in interface IRfGap

Returns:

the ETL product of the gap (in volts ).

getPhase

public double getPhase()

Return the RF phase delay of the gap with respect to the synchronous particle.

Specified by:

getPhase in interface IRfGap

Returns:

phase delay w.r.t. synchronous particle (in radians ).

getFrequency

public double getFrequency()

Get the operating frequency of the RF gap.

Specified by:

getFrequency in interface IRfGap

Returns:

frequency of RF gap (in Hertz )

isFirstCell

public boolean isFirstCell()

return whether this gap is the initial gap of a cavity

Returns:

The firstGap value

setETL

public void setETL(double dblETL)

Set the ETL product of the RF gap where E is the longitudinal electric field of the gap, T is the transit time factor of the gap, L is the length of the gap.

The maximum energy gain from the gap is given by qETL where q is the charge (in coulombs) of the species particle.

Specified by:

setETL in interface IRfGap

Parameters:

dblETL - ETL product of gap (in volts ).

setPhase

public void setPhase(double dblPhase)

Set the phase delay of the RF in gap with respect to the synchronous particle. The actual energy gain from the gap is given by qETLcos(dblPhi) where dbkPhi is the phase delay.

Specified by:

setPhase in interface IRfGap

Parameters:

dblPhase - phase delay of the RF w.r.t. synchronous particle (in radians ).

setFrequency

public void setFrequency(double dblFreq)

Set the operating frequency of the RF gap.

Specified by:

setFrequency in interface IRfGap

Parameters:

dblFreq - frequency of RF gap (in Hertz )

setE0

public void setE0(double e)

Set the on accelerating field @ param E - the on axis field (V/m)

Specified by:

setE0 in interface IRfGap

Parameters:

e - The new e0 value

getE0

public double getE0()

Get the on accelerating field (V/m)

Specified by:

getE0 in interface IRfGap

Returns:

The e0 value

getCellLength

public double getCellLength()

return the cell length (m)

Returns:

The cellLength value

wavelengthRF

public double wavelengthRF()

Compute the wavelength of the RF.

Returns:

RF wavelength in meters

betaMidGap

public double betaMidGap(IProbe probe)

Compute and return the mid-gap normalized velocity for the given probe. NOTE: - Because of the state-dependent nature of the energy calculations (this needs to be fixed), this function will only work correctly if the function energyGain() is consistent.

Parameters:

probe - probe containing energy information

Returns:

average or "mid-gap" velocity in units of c

See Also:

• energyGain(IProbe)

elapsedTime

public double elapsedTime(IProbe probe)

Returns the time taken for the probe to propagate through element.

Specified by:

elapsedTime in class ThinElement

Parameters:

probe - propagating probe

Returns:

value of zero

energyGain

public double energyGain(IProbe probe)

Compute the energy gain of the RF gap for a probe including the effects of calculating the phase advance.

Specified by:

energyGain in class ThinElement

Parameters:

probe - uses the particle species charge

Returns:

energy gain for this probe (in electron-volts )

transferMap

protected PhaseMap transferMap(IProbe probe)
                        throws ModelException

Compute the transfer map for an ideal RF gap.

Specified by:

transferMap in class ThinElement

Parameters:

probe - compute transfer map using parameters from this probe

Returns:

transfer map for the probe

Throws:

ModelException - this should not occur

simpleEnergyGain

public double simpleEnergyGain(IProbe probe)

Compute the energy gain of the RF gap for a probe assuming a fixed default phase at the gap center.

Parameters:

probe - uses the particle species charge

Returns:

energy gain for this probe (in electron-volts )

compTransFocusing

public double compTransFocusing(IProbe probe)

Get the transverse focusing constant for a particular probe. The focusing constant is used in the construction of the transfer matrix for the RF gap. A gap provides longitudinal focusing and transverse defocusing as well as a gain in beam energy. This focusing constant describes the effect in the transverse direction, which is defocusing and, therefore, negative.

The value represents the thin lens focusing constant for an ideal RF gap (this is the inverse of the focal length). To compute the focusing action for the lens we must include beam energy, which is changing through the gap. We use the value of beta for which the beam has received half the total energy gain.

Parameters:

probe - beam energy and particle charge are taken from the probe

Returns:

(de)focusing constant (in radians/meter )

compLongFocusing

public double compLongFocusing(IProbe probe)

Get the longitudinal focusing constant for a particular probe. The focusing constant is used in the construction of the transfer matrix for the RF gap. A gap provides longitudinal focusing and transverse defocusing as well as a gain in beam energy. This focusing constant describes the effect in the longitudinal direction, which is focusing and, therefore, positive.

The value represents the thin lens focusing constant for an ideal RF gap (this is the inverse of the focal length). To compute the focusing action for the lens we must include beam energy, which is changing through the gap. We use the value of beta for which the beam has received half the total energy gain.

Parameters:

probe - beam energy and particle charge are taken from the probe

Returns:

(de)focusing constant (in radians/meter )

print

public void print(PrintWriter os)

Dump current state and content to output stream.

Overrides:

print in class Element

Parameters:

os - output stream object

initializeFrom

public void initializeFrom(LatticeElement element)

Conversion method to be provided by the user

Specified by:

initializeFrom in interface IComponent

Overrides:

initializeFrom in class Element

Parameters:

element - the SMF node to convert

computeSynchronousPhaseAndEnergyGain

public void computeSynchronousPhaseAndEnergyGain(IProbe probe)

Description copied from interface: IRfGap

Compute the synchronous phase and the energy gain for a cavity gap.

Specified by:

computeSynchronousPhaseAndEnergyGain in interface IRfGap

getSynchronousPhase

public double getSynchronousPhase()

Description copied from interface: IRfGap

Return the synchronous phase of a cavity gap, which must be previously calculated using computeSynchronousPhase.

Specified by:

getSynchronousPhase in interface IRfGap

Returns:

synchronous phase [rad]

getEnergyGain

public double getEnergyGain()

Description copied from interface: IRfGap

Return the energy gain of a cavity gap previously calculated.

Specified by:

getEnergyGain in interface IRfGap

Returns: