Functions
void	DepositCharge1D (impactx::ImpactXParticleContainer &myspc, amrex::Gpu::DeviceVector< amrex::Real > &charge_distribution, amrex::Real bin_min, amrex::Real bin_size, bool is_unity_particle_weight)

void	DerivativeCharge1D (amrex::Gpu::DeviceVector< amrex::Real > const &charge_distribution, amrex::Gpu::DeviceVector< amrex::Real > &slopes, amrex::Real bin_size, bool GetNumberDensity)

void	MeanTransversePosition (impactx::ImpactXParticleContainer &myspc, amrex::Gpu::DeviceVector< amrex::Real > &mean_x, amrex::Gpu::DeviceVector< amrex::Real > &mean_y, amrex::Real bin_min, amrex::Real bin_size, bool is_unity_particle_weight)

template<typename VariantType>
std::tuple< bool, amrex::Real >	CSRBendElement (VariantType const &element_variant, RefPart const &refpart)

template<typename T_Element>
void	HandleISR (impactx::ImpactXParticleContainer &particle_container, T_Element const &element_variant, amrex::Real slice_ds)

template<typename T_Element>
void	HandleWakefield (impactx::ImpactXParticleContainer &particle_container, T_Element const &element_variant, amrex::Real slice_ds, bool print_wakefield=false)

template<typename VariantType>
std::tuple< bool, amrex::Real >	ISRBendElement (VariantType const &element_variant, RefPart const &refpart)

void	ISRPush (ImpactXParticleContainer &pc, amrex::ParticleReal slice_ds, amrex::ParticleReal rc, int isr_order)

amrex::Real	alpha (amrex::Real s)

amrex::Real	w_t_rf (amrex::Real s, amrex::Real a, amrex::Real g, amrex::Real L)

amrex::Real	w_l_rf (amrex::Real s, amrex::Real a, amrex::Real g, amrex::Real L)

amrex::Gpu::DeviceVector< amrex::Real >	convolve_fft (amrex::Gpu::DeviceVector< amrex::Real > const &beam_profile_slope, amrex::Gpu::DeviceVector< amrex::Real > const &wake_func, amrex::Real delta_t)

AMREX_GPU_HOST_DEVICE AMREX_FORCE_INLINE amrex::Real	unit_step (amrex::Real s)

AMREX_GPU_HOST_DEVICE AMREX_FORCE_INLINE amrex::Real	w_l_csr (amrex::Real s, amrex::Real R, amrex::Real const bin_size)

void	WakePush (ImpactXParticleContainer &pc, amrex::Gpu::DeviceVector< amrex::Real > const &convolved_wakefield, amrex::ParticleReal slice_ds, amrex::Real bin_size, amrex::Real bin_min)

Variables
constexpr amrex::Real	Z0 = 377
	Free space impedance [Ohm].

constexpr amrex::Real	alpha_1 = 0.4648

Function Documentation

◆ alpha()

amrex::Real impactx::particles::wakefields::alpha ( amrex::Real s )

Alpha Function

Eq. (21) in: K. L.F. Bane, "Short-Range Dipole Wakefields in Accelerating Structures for the NLC," SLAC-PUB-9663, 2003

Parameters

s	value along s [m]

Returns: value of alpha(s) in Eq. (21) of Bane, 2003

◆ convolve_fft()

amrex::Gpu::DeviceVector< amrex::Real > impactx::particles::wakefields::convolve_fft	(	amrex::Gpu::DeviceVector< amrex::Real > const &	beam_profile_slope,
		amrex::Gpu::DeviceVector< amrex::Real > const &	wake_func,
		amrex::Real	delta_t )

Perform FFT-based convolution

Parameters

[in]	beam_profile_slope	number density slope along s [1/m]
[in]	wake_func	wake function along s [V*pc/mm]
[in]	delta_t	size of a bin in wake_func [m]

Returns: FFT convolution of beam_profile_slope & wake_func (N = len(beam_profile_slope) = len(wake_func)/2)

◆ CSRBendElement()

template<typename VariantType>

std::tuple< bool, amrex::Real > impactx::particles::wakefields::CSRBendElement	(	VariantType const &	element_variant,
		RefPart const &	refpart )

Function to calculate the radius of curvature (R) and check if an element has CSR

Parameters

[in]	element_variant	the lattice element to check
[in]	refpart	reference particle

Returns: boolean flag indicating if the element has CSR, radius of curvature (or zero)

◆ DepositCharge1D()

void impactx::particles::wakefields::DepositCharge1D	(	impactx::ImpactXParticleContainer &	myspc,
		amrex::Gpu::DeviceVector< amrex::Real > &	charge_distribution,
		amrex::Real	bin_min,
		amrex::Real	bin_size,
		bool	is_unity_particle_weight = false )

Function to calculate charge density profile

Parameters

[in]	myspc	the particle species to deposit along s
[out]	charge_distribution	the output array (1D)
[in]	bin_min	lower end of the beam in s
[in]	bin_size	size of the beam in s divided by num_bins
[in]	is_unity_particle_weight	ignore the particle weighting per macro particle, otherwise treat each particle as one physical particle

◆ DerivativeCharge1D()

void impactx::particles::wakefields::DerivativeCharge1D	(	amrex::Gpu::DeviceVector< amrex::Real > const &	charge_distribution,
		amrex::Gpu::DeviceVector< amrex::Real > &	slopes,
		amrex::Real	bin_size,
		bool	GetNumberDensity = true )

Function to calculate the slope of the number (or charge) density

Parameters

[in]	charge_distribution	deposited charge in 1D along s
[out]	slopes	derivative of charge_distribution along s with len(charge_distribution)-1
[in]	bin_size	size of the beam in s divided by num_bins
[in]	GetNumberDensity	number density if true, otherwise charge density

◆ HandleISR()

template<typename T_Element>

void impactx::particles::wakefields::HandleISR	(	impactx::ImpactXParticleContainer &	particle_container,
		T_Element const &	element_variant,
		amrex::Real	slice_ds )

Function to handle ISR in bending dipoles.

Parameters

[in]	particle_container	the particle species container
[in]	element_variant	variant type of the lattice element
[in]	slice_ds	slice spacing along s

◆ HandleWakefield()

template<typename T_Element>

void impactx::particles::wakefields::HandleWakefield	(	impactx::ImpactXParticleContainer &	particle_container,
		T_Element const &	element_variant,
		amrex::Real	slice_ds,
		bool	print_wakefield = false )

Function to handle CSR bending process including charge deposition, mean transverse position calculation, wakefield generation, and convolution.

Parameters

[in]	particle_container	the particle species container
[in]	element_variant	variant type of the lattice element
[in]	slice_ds	slice spacing along s
[in]	print_wakefield	for debugging: print the wakefield to convolved_wakefield.txt

◆ ISRBendElement()

template<typename VariantType>

std::tuple< bool, amrex::Real > impactx::particles::wakefields::ISRBendElement	(	VariantType const &	element_variant,
		RefPart const &	refpart )

Function to calculate the radius of curvature (R) and check if an element has ISR

Parameters

[in]	element_variant	the lattice element to check
[in]	refpart	reference particle

Returns: boolean flag indicating if the element has ISR, radius of curvature (or zero)

◆ ISRPush()

void impactx::particles::wakefields::ISRPush	(	ImpactXParticleContainer &	pc,
		amrex::ParticleReal	slice_ds,
		amrex::ParticleReal	rc,
		int	isr_order )

Function to update particle momentum using a kick due to incoherent synchrotron radiation (ISR).

Parameters

[in,out]	pc	the particle species container
[in]	slice_ds	slice spacing [m]
[in]	rc	bending radius [m]
[in]	isr_order	order of quantum ISR effects

◆ MeanTransversePosition()

void impactx::particles::wakefields::MeanTransversePosition	(	impactx::ImpactXParticleContainer &	myspc,
		amrex::Gpu::DeviceVector< amrex::Real > &	mean_x,
		amrex::Gpu::DeviceVector< amrex::Real > &	mean_y,
		amrex::Real	bin_min,
		amrex::Real	bin_size,
		bool	is_unity_particle_weight = false )

Function to calculate the mean transverse positions (x and y) at each bin along s

Parameters

[in]	myspc	the particle species to deposit along s
[out]	mean_x	the output array for mean x positions (1D)
[out]	mean_y	the output array for mean y positions (1D)
[in]	bin_min	lower end of the beam in s
[in]	bin_size	size of the beam in s divided by num_bins
[in]	is_unity_particle_weight	ignore the particle weighting per macro particle, otherwise treat each particle as one physical particle

◆ unit_step()

AMREX_GPU_HOST_DEVICE AMREX_FORCE_INLINE amrex::Real impactx::particles::wakefields::unit_step ( amrex::Real s )

Step Function (Heavy-Side)

Parameters

s	value along s [m]

Returns: returns 1 if s>0, else 0

◆ w_l_csr()

AMREX_GPU_HOST_DEVICE AMREX_FORCE_INLINE amrex::Real impactx::particles::wakefields::w_l_csr	(	amrex::Real	s,
		amrex::Real	R,
		amrex::Real const	bin_size )

CSR Wake Function

Eq. (28) in: E.L. Saldin et al., "On the coherent radiation of an electron bunch moving in an arc of a circle", NiMA Volume 398, Issues 2–3, Pages 373-394, 21 October (1997) https://doi.org/10.1016/S0168-9002(97)00822-X

Parameters

[in]	s	value along s [m]
[in]	R	band radius [m]
[in]	bin_size	longitudinal bin size [m]

Returns: wake functions in [V*pc/mm]

◆ w_l_rf()

amrex::Real impactx::particles::wakefields::w_l_rf	(	amrex::Real	s,
		amrex::Real	a,
		amrex::Real	g,
		amrex::Real	L )

Resistive Wall Wake Function (longitudinal)

Eq. (18) in: K. L.F. Bane, "Short-Range Dipole Wakefields in Accelerating Structures for the NLC," SLAC-PUB-9663, 2003

Parameters

[in]	s	value along s [m]
[in]	a	iris radius [m]
[in]	g	gap [m]
[in]	L	period length [m]

Returns: longitudinal wake field [V/m/pC/mm]

◆ w_t_rf()

amrex::Real impactx::particles::wakefields::w_t_rf	(	amrex::Real	s,
		amrex::Real	a,
		amrex::Real	g,
		amrex::Real	L )

Resistive Wall Wake Function (transverse)

Eq. (17) in: K. L.F. Bane, "Short-Range Dipole Wakefields in Accelerating Structures for the NLC," SLAC-PUB-9663, 2003

Parameters

[in]	s	value along s [m]
[in]	a	iris radius [m]
[in]	g	gap [m]
[in]	L	period length [m]

Returns: transverse wake field [V/m/pC/mm]

◆ WakePush()

void impactx::particles::wakefields::WakePush	(	ImpactXParticleContainer &	pc,
		amrex::Gpu::DeviceVector< amrex::Real > const &	convolved_wakefield,
		amrex::ParticleReal	slice_ds,
		amrex::Real	bin_size,
		amrex::Real	bin_min )

Function to update particle momentum using wake force kick

Parameters

[in,out]	pc	the particle species container
[in]	convolved_wakefield	wake functions in [V*pc/mm]
[in]	slice_ds	slice spacing along s
[in]	bin_size	size of the beam in s divided by num_bins
[in]	bin_min	lower end of the beam in s

Variable Documentation

◆ alpha_1

amrex::Real impactx::particles::wakefields::alpha_1 = 0.4648

constexpr

Wake function constant [unitless]

Used in eq. (21) of: K. L.F. Bane, "Short-Range Dipole Wakefields in Accelerating Structures for the NLC," SLAC-PUB-9663, 2003

◆ Z0

amrex::Real impactx::particles::wakefields::Z0 = 377

constexpr

Free space impedance [Ohm].

Functions

Variables

Function Documentation

◆ alpha()

◆ convolve_fft()

◆ CSRBendElement()

◆ DepositCharge1D()

◆ DerivativeCharge1D()

◆ HandleISR()

◆ HandleWakefield()

◆ ISRBendElement()

◆ ISRPush()

◆ MeanTransversePosition()

◆ unit_step()

◆ w_l_csr()

◆ w_l_rf()

◆ w_t_rf()

◆ WakePush()

Variable Documentation

◆ alpha_1

◆ Z0