ImpactX
Drift.H
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1 /* Copyright 2022-2023 The Regents of the University of California, through Lawrence
2  * Berkeley National Laboratory (subject to receipt of any required
3  * approvals from the U.S. Dept. of Energy). All rights reserved.
4  *
5  * This file is part of ImpactX.
6  *
7  * Authors: Chad Mitchell, Axel Huebl
8  * License: BSD-3-Clause-LBNL
9  */
10 #ifndef IMPACTX_DRIFT_H
11 #define IMPACTX_DRIFT_H
12 
14 #include "mixin/beamoptic.H"
15 #include "mixin/thick.H"
16 #include "mixin/nofinalize.H"
17 
18 #include <AMReX_Extension.H>
19 #include <AMReX_REAL.H>
20 
21 #include <cmath>
22 
23 
24 namespace impactx
25 {
26  struct Drift
27  : public elements::BeamOptic<Drift>,
28  public elements::Thick,
30  {
31  static constexpr auto name = "Drift";
33 
39  Drift( amrex::ParticleReal const ds, int const nslice )
40  : Thick(ds, nslice)
41  {
42  }
43 
45  using BeamOptic::operator();
46 
57  PType& AMREX_RESTRICT p,
58  amrex::ParticleReal & AMREX_RESTRICT px,
59  amrex::ParticleReal & AMREX_RESTRICT py,
60  amrex::ParticleReal & AMREX_RESTRICT pt,
61  RefPart const & refpart) const {
62 
63  using namespace amrex::literals; // for _rt and _prt
64 
65  // access AoS data such as positions and cpu/id
66  amrex::ParticleReal const x = p.pos(RealAoS::x);
67  amrex::ParticleReal const y = p.pos(RealAoS::y);
68  amrex::ParticleReal const t = p.pos(RealAoS::t);
69 
70  // initialize output values of momenta
71  amrex::ParticleReal const pxout = px;
72  amrex::ParticleReal const pyout = py;
73  amrex::ParticleReal const ptout = pt;
74 
75  // length of the current slice
76  amrex::ParticleReal const slice_ds = m_ds / nslice();
77 
78  // access reference particle values to find beta*gamma^2
79  amrex::ParticleReal const pt_ref = refpart.pt;
80  amrex::ParticleReal const betgam2 = pow(pt_ref, 2) - 1.0_prt;
81 
82  // advance position and momentum (drift)
83  p.pos(RealAoS::x) = x + slice_ds * px;
84  // pxout = px;
85  p.pos(RealAoS::y) = y + slice_ds * py;
86  // pyout = py;
87  p.pos(RealAoS::t) = t + (slice_ds/betgam2) * pt;
88  // ptout = pt;
89 
90  // assign updated momenta
91  px = pxout;
92  py = pyout;
93  pt = ptout;
94 
95  }
96 
102  void operator() (RefPart & AMREX_RESTRICT refpart) const {
103 
104  using namespace amrex::literals; // for _rt and _prt
105 
106  // assign input reference particle values
107  amrex::ParticleReal const x = refpart.x;
108  amrex::ParticleReal const px = refpart.px;
109  amrex::ParticleReal const y = refpart.y;
110  amrex::ParticleReal const py = refpart.py;
111  amrex::ParticleReal const z = refpart.z;
112  amrex::ParticleReal const pz = refpart.pz;
113  amrex::ParticleReal const t = refpart.t;
114  amrex::ParticleReal const pt = refpart.pt;
115  amrex::ParticleReal const s = refpart.s;
116 
117  // length of the current slice
118  amrex::ParticleReal const slice_ds = m_ds / nslice();
119 
120  // assign intermediate parameter
121  amrex::ParticleReal const step = slice_ds / sqrt(pow(pt,2)-1.0_prt);
122 
123  // advance position and momentum (drift)
124  refpart.x = x + step*px;
125  refpart.y = y + step*py;
126  refpart.z = z + step*pz;
127  refpart.t = t - step*pt;
128 
129  // advance integrated path length
130  refpart.s = s + slice_ds;
131 
132  }
133  };
134 
135 } // namespace impactx
136 
137 #endif // IMPACTX_DRIFT_H
#define AMREX_FORCE_INLINE
#define AMREX_GPU_HOST_DEVICE
AMREX_GPU_HOST_DEVICE AMREX_FORCE_INLINE GpuComplex< T > pow(const GpuComplex< T > &a_z, const T &a_y) noexcept
AMREX_GPU_HOST_DEVICE AMREX_FORCE_INLINE GpuComplex< T > sqrt(const GpuComplex< T > &a_z) noexcept
Definition: ImpactX.cpp:34
s
Definition: Drift.H:30
Drift(amrex::ParticleReal const ds, int const nslice)
Definition: Drift.H:39
ImpactXParticleContainer::ParticleType PType
Definition: Drift.H:32
static constexpr auto name
Definition: Drift.H:31
AMREX_GPU_HOST_DEVICE AMREX_FORCE_INLINE void operator()(PType &AMREX_RESTRICT p, amrex::ParticleReal &AMREX_RESTRICT px, amrex::ParticleReal &AMREX_RESTRICT py, amrex::ParticleReal &AMREX_RESTRICT pt, RefPart const &refpart) const
Definition: Drift.H:56
@ x
position in x [m] (at fixed s OR fixed t)
Definition: ImpactXParticleContainer.H:42
@ y
position in y [m] (at fixed s OR fixed t)
Definition: ImpactXParticleContainer.H:43
@ t
c * time-of-flight [m] (at fixed s)
Definition: ImpactXParticleContainer.H:44
Definition: ReferenceParticle.H:30
amrex::ParticleReal pt
energy, normalized by rest energy
Definition: ReferenceParticle.H:39
Definition: beamoptic.H:135
Definition: nofinalize.H:22
Definition: thick.H:24
AMREX_GPU_HOST_DEVICE AMREX_FORCE_INLINE amrex::ParticleReal ds() const
Definition: thick.H:50
AMREX_GPU_HOST_DEVICE AMREX_FORCE_INLINE int nslice() const
Definition: thick.H:40
amrex::ParticleReal m_ds
Definition: thick.H:56
Thick(amrex::ParticleReal const ds, int const nslice)
Definition: thick.H:30