ImpactX
ExactDrift.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_EXACTDRIFT_H
11 #define IMPACTX_EXACTDRIFT_H
12 
14 #include "mixin/alignment.H"
15 #include "mixin/beamoptic.H"
16 #include "mixin/thick.H"
17 #include "mixin/nofinalize.H"
18 
19 #include <AMReX_Extension.H>
20 #include <AMReX_REAL.H>
21 
22 #include <cmath>
23 
24 
25 namespace impactx
26 {
27  struct ExactDrift
28  : public elements::BeamOptic<ExactDrift>,
29  public elements::Thick,
30  public elements::Alignment,
32  {
33  static constexpr auto name = "ExactDrift";
35 
45  amrex::ParticleReal ds,
46  amrex::ParticleReal dx = 0,
47  amrex::ParticleReal dy = 0,
48  amrex::ParticleReal rotation_degree = 0,
49  int nslice = 1
50  )
51  : Thick(ds, nslice),
52  Alignment(dx, dy, rotation_degree)
53  {
54  }
55 
57  using BeamOptic::operator();
58 
73  amrex::ParticleReal & AMREX_RESTRICT x,
74  amrex::ParticleReal & AMREX_RESTRICT y,
75  amrex::ParticleReal & AMREX_RESTRICT t,
76  amrex::ParticleReal & AMREX_RESTRICT px,
77  amrex::ParticleReal & AMREX_RESTRICT py,
78  amrex::ParticleReal & AMREX_RESTRICT pt,
79  [[maybe_unused]] uint64_t & AMREX_RESTRICT idcpu,
80  RefPart const & refpart
81  ) const
82  {
83  using namespace amrex::literals; // for _rt and _prt
84 
85  // shift due to alignment errors of the element
86  shift_in(x, y, px, py);
87 
88  // initialize output values
89  amrex::ParticleReal const xout = x;
90  amrex::ParticleReal const yout = y;
91  amrex::ParticleReal const tout = t;
92 
93  // initialize output values of momenta
94  amrex::ParticleReal const pxout = px;
95  amrex::ParticleReal const pyout = py;
96  amrex::ParticleReal const ptout = pt;
97 
98  // length of the current slice
99  amrex::ParticleReal const slice_ds = m_ds / nslice();
100 
101  // access reference particle values to find beta, beta*gamma
102  amrex::ParticleReal const bet = refpart.beta();
103  amrex::ParticleReal const betgam = refpart.beta_gamma();
104 
105  // compute the radical in the denominator (= pz):
106  amrex::ParticleReal const pzden = sqrt(pow(pt-1_prt/bet,2) -
107  1_prt/pow(betgam,2) - pow(px,2) - pow(py,2));
108 
109  // advance position and momentum (exact drift)
110  x = xout + slice_ds * px / pzden;
111  // pxout = px;
112  y = yout + slice_ds * py / pzden;
113  // pyout = py;
114  t = tout - slice_ds * (1_prt / bet + (pt-1_prt/bet)/pzden);
115  // ptout = pt;
116 
117  // assign updated momenta
118  px = pxout;
119  py = pyout;
120  pt = ptout;
121 
122  // undo shift due to alignment errors of the element
123  shift_out(x, y, px, py);
124  }
125 
131  void operator() (RefPart & AMREX_RESTRICT refpart) const {
132 
133  using namespace amrex::literals; // for _rt and _prt
134 
135  // assign input reference particle values
136  amrex::ParticleReal const x = refpart.x;
137  amrex::ParticleReal const px = refpart.px;
138  amrex::ParticleReal const y = refpart.y;
139  amrex::ParticleReal const py = refpart.py;
140  amrex::ParticleReal const z = refpart.z;
141  amrex::ParticleReal const pz = refpart.pz;
142  amrex::ParticleReal const t = refpart.t;
143  amrex::ParticleReal const pt = refpart.pt;
144  amrex::ParticleReal const s = refpart.s;
145 
146  // length of the current slice
147  amrex::ParticleReal const slice_ds = m_ds / nslice();
148 
149  // assign intermediate parameter
150  amrex::ParticleReal const step = slice_ds / sqrt(pow(pt,2)-1.0_prt);
151 
152  // advance position and momentum (drift)
153  refpart.x = x + step*px;
154  refpart.y = y + step*py;
155  refpart.z = z + step*pz;
156  refpart.t = t - step*pt;
157 
158  // advance integrated path length
159  refpart.s = s + slice_ds;
160 
161  }
162  };
163 
164 } // namespace impactx
165 
166 #endif // IMPACTX_EXACTDRIFT_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:33
@ t
fixed t as the independent variable
s
Definition: ExactDrift.H:32
ExactDrift(amrex::ParticleReal ds, amrex::ParticleReal dx=0, amrex::ParticleReal dy=0, amrex::ParticleReal rotation_degree=0, int nslice=1)
Definition: ExactDrift.H:44
static constexpr auto name
Definition: ExactDrift.H:33
AMREX_GPU_HOST_DEVICE AMREX_FORCE_INLINE void operator()(amrex::ParticleReal &AMREX_RESTRICT x, amrex::ParticleReal &AMREX_RESTRICT y, amrex::ParticleReal &AMREX_RESTRICT t, amrex::ParticleReal &AMREX_RESTRICT px, amrex::ParticleReal &AMREX_RESTRICT py, amrex::ParticleReal &AMREX_RESTRICT pt, [[maybe_unused]] uint64_t &AMREX_RESTRICT idcpu, RefPart const &refpart) const
Definition: ExactDrift.H:72
ImpactXParticleContainer::ParticleType PType
Definition: ExactDrift.H:34
Definition: ReferenceParticle.H:30
AMREX_GPU_HOST_DEVICE AMREX_FORCE_INLINE amrex::ParticleReal beta_gamma() const
Definition: ReferenceParticle.H:79
AMREX_GPU_HOST_DEVICE AMREX_FORCE_INLINE amrex::ParticleReal beta() const
Definition: ReferenceParticle.H:64
Definition: alignment.H:27
AMREX_GPU_HOST_DEVICE AMREX_FORCE_INLINE void shift_out(amrex::ParticleReal &AMREX_RESTRICT x, amrex::ParticleReal &AMREX_RESTRICT y, amrex::ParticleReal &AMREX_RESTRICT px, amrex::ParticleReal &AMREX_RESTRICT py) const
Definition: alignment.H:91
AMREX_GPU_HOST_DEVICE AMREX_FORCE_INLINE amrex::ParticleReal dx() const
Definition: alignment.H:120
AMREX_GPU_HOST_DEVICE AMREX_FORCE_INLINE void shift_in(amrex::ParticleReal &AMREX_RESTRICT x, amrex::ParticleReal &AMREX_RESTRICT y, amrex::ParticleReal &AMREX_RESTRICT px, amrex::ParticleReal &AMREX_RESTRICT py) const
Definition: alignment.H:61
AMREX_GPU_HOST_DEVICE AMREX_FORCE_INLINE amrex::ParticleReal dy() const
Definition: alignment.H:130
Definition: beamoptic.H:149
Definition: nofinalize.H:22
Definition: thick.H:24
Thick(amrex::ParticleReal ds, int nslice)
Definition: thick.H:30
AMREX_GPU_HOST_DEVICE AMREX_FORCE_INLINE amrex::ParticleReal ds() const
Definition: thick.H:53
AMREX_GPU_HOST_DEVICE AMREX_FORCE_INLINE int nslice() const
Definition: thick.H:43
amrex::ParticleReal m_ds
Definition: thick.H:58