ImpactX
Multipole.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_MULTIPOLE_H
11 #define IMPACTX_MULTIPOLE_H
12 
14 #include "mixin/beamoptic.H"
15 #include "mixin/thin.H"
16 #include "mixin/nofinalize.H"
17 
18 #include <AMReX_Extension.H>
19 #include <AMReX_REAL.H>
20 #include <AMReX_GpuComplex.H>
21 
22 #include <cmath>
23 
24 namespace impactx
25 {
26  struct Multipole
27  : public elements::BeamOptic<Multipole>,
28  public elements::Thin,
30  {
31  static constexpr auto name = "Multipole";
33 
40  Multipole( int const multipole,
41  amrex::ParticleReal const K_normal,
42  amrex::ParticleReal const K_skew )
43  : m_multipole(multipole), m_Kn(K_normal), m_Ks(K_skew)
44  {
45  // compute factorial of multipole index
46  int const m = m_multipole - 1;
47  m_mfactorial = 1;
48  for( int n = 1; n < m + 1; n = n + 1 ) {
49  m_mfactorial *= n;
50  }
51  }
52 
54  using BeamOptic::operator();
55 
67  PType& AMREX_RESTRICT p,
68  amrex::ParticleReal & AMREX_RESTRICT px,
69  amrex::ParticleReal & AMREX_RESTRICT py,
70  amrex::ParticleReal & AMREX_RESTRICT pt,
71  [[maybe_unused]] RefPart const & refpart) const {
72 
73  using namespace amrex::literals; // for _rt and _prt
74 
75  // a complex type with two amrex::ParticleReal
77 
78  // access AoS data such as positions and cpu/id
79  amrex::ParticleReal const x = p.pos(RealAoS::x);
80  amrex::ParticleReal const y = p.pos(RealAoS::y);
81  amrex::ParticleReal const t = p.pos(RealAoS::t);
82 
83  // access reference particle values to find (beta*gamma)^2
84  //amrex::ParticleReal const pt_ref = refpart.pt;
85  //amrex::ParticleReal const betgam2 = pow(pt_ref, 2) - 1.0_prt;
86 
87  // intialize output values of momenta
88  amrex::ParticleReal pxout = px;
89  amrex::ParticleReal pyout = py;
90  amrex::ParticleReal ptout = pt;
91 
92  // assign complex position and complex multipole strength
93  Complex const zeta(x, y);
94  Complex const alpha(m_Kn, m_Ks);
95 
96  // compute complex momentum kick
97  int const m = m_multipole - 1;
98  Complex kick = amrex::pow(zeta, m);
99  kick *= alpha;
100  amrex::ParticleReal const dpx = -1.0_prt*kick.m_real/m_mfactorial;
101  amrex::ParticleReal const dpy = kick.m_imag/m_mfactorial;
102 
103  // advance position and momentum
104  p.pos(RealAoS::x) = x;
105  pxout = px + dpx;
106 
107  p.pos(RealAoS::y) = y;
108  pyout = py + dpy;
109 
110  p.pos(RealAoS::t) = t;
111  ptout = pt;
112 
113  // assign updated momenta
114  px = pxout;
115  py = pyout;
116  pt = ptout;
117 
118  }
119 
121  using Thin::operator();
122 
123  private:
126  amrex::ParticleReal m_Kn;
127  amrex::ParticleReal m_Ks;
128 
129  };
130 
131 } // namespace impactx
132 
133 #endif // IMPACTX_MULTIPOLE_H
#define AMREX_FORCE_INLINE
#define AMREX_GPU_HOST_DEVICE
fftw_complex Complex
AMREX_GPU_HOST_DEVICE AMREX_FORCE_INLINE GpuComplex< T > pow(const GpuComplex< T > &a_z, const T &a_y) noexcept
Definition: ImpactX.cpp:33
int n
Definition: Multipole.H:30
Multipole(int const multipole, amrex::ParticleReal const K_normal, amrex::ParticleReal const K_skew)
Definition: Multipole.H:40
amrex::ParticleReal m_Kn
factorial of multipole index
Definition: Multipole.H:126
int m_mfactorial
multipole index
Definition: Multipole.H:125
ImpactXParticleContainer::ParticleType PType
Definition: Multipole.H:32
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, [[maybe_unused]] RefPart const &refpart) const
Definition: Multipole.H:66
amrex::ParticleReal m_Ks
integrated normal multipole coefficient
Definition: Multipole.H:127
static constexpr auto name
Definition: Multipole.H:31
int m_multipole
Definition: Multipole.H:124
@ 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
Definition: beamoptic.H:135
Definition: nofinalize.H:22
Definition: thin.H:24