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/* Copyright 2020 Luca Fedeli, Neil Zaim
*
* This file is part of WarpX.
*
* License: BSD-3-Clause-LBNL
*/
#ifndef QED_SCHWINGER_PROCESS_H_
#define QED_SCHWINGER_PROCESS_H_
#include "Particles/ElementaryProcess/QEDInternals/SchwingerProcessWrapper.H"
#include "Utils/TextMsg.H"
/**
* This structure is a functor which calls getSchwingerProductionNumber to
* calculate the number of pairs created during a given timestep at a given cell.
*/
struct SchwingerFilterFunc
{
const int m_threshold_poisson_gaussian;
const amrex::Real m_dV;
const amrex::Real m_dt;
/** Get the number of created pairs in a given cell at a given timestep.
*
* \tparam FABs the src array of Array4 type
*
* @param[in] src_FABs A class with 6 named Array4 that contain the EM field in the tile.
* @param[in] i index of the cell in the first direction.
* @param[in] j index of the cell in the second direction.
* @param[in] k index of the cell in the third direction.
* @param[in] engine the random number state and factory
* @return the number of pairs created in the cell.
*/
template <typename FABs>
AMREX_GPU_HOST_DEVICE AMREX_FORCE_INLINE
amrex::Real operator() (const FABs& src_FABs,
const int i, const int j, const int k,
amrex::RandomEngine const& engine) const noexcept
{
const auto& arrEx = src_FABs.Ex;
const auto& arrEy = src_FABs.Ey;
const auto& arrEz = src_FABs.Ez;
const auto& arrBx = src_FABs.Bx;
const auto& arrBy = src_FABs.By;
const auto& arrBz = src_FABs.Bz;
return getSchwingerProductionNumber( m_dV, m_dt,
arrEx(i,j,k),arrEy(i,j,k),arrEz(i,j,k),
arrBx(i,j,k),arrBy(i,j,k),arrBz(i,j,k),
m_threshold_poisson_gaussian,engine);
}
};
/**
* This structure is a functor which assigns a weight to particles created via
* the Schwinger process.
*/
struct SchwingerTransformFunc
{
const amrex::Real m_y_size;
const int m_weight_index;
/** Assign a weight to particles created via the Schwinger process.
*
* \tparam DstTile the dst particle tile type
*
* @param[in,out] dst1 Target electron species.
* @param[in,out] dst2 Target photon species.
* @param[in] i_dst1 Particle index of target electron species.
* @param[in] i_dst2 Particle index of target positron species.
* @param[in] N Number of particles created per cell per species.
* @param[in] total_weight Number of physical pairs created in the
* considered cell.
*/
template <typename DstTile>
AMREX_GPU_HOST_DEVICE AMREX_FORCE_INLINE
void operator() (DstTile& dst1, DstTile& dst2, const int i_dst1,
const int i_dst2, const int N,
const amrex::Real total_weight) const noexcept
{
for (int n = 0; n < N; ++n){
#if defined(WARPX_DIM_1D_Z)
amrex::ignore_unused(dst1, dst2, i_dst1, i_dst2, N, total_weight);
amrex::Abort("SchwingerTransformFunc not implemented in 1D");
#elif defined(WARPX_DIM_3D)
dst1.m_rdata[m_weight_index][i_dst1+n] = total_weight/N;
dst2.m_rdata[m_weight_index][i_dst2+n] = total_weight/N;
#elif defined(WARPX_DIM_XZ) || defined(WARPX_DIM_RZ)
dst1.m_rdata[m_weight_index][i_dst1+n] = total_weight/N/m_y_size;
dst2.m_rdata[m_weight_index][i_dst2+n] = total_weight/N/m_y_size;
#endif
}
}
};
#endif // QED_SCHWINGER_PROCESS_H_
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