LF2.hpp

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//
// Class LF2
//   Second order Leap-Frog time integrator
//
// Copyright (c) 2008 - 2020, Paul Scherrer Institut, Villigen PSI, Switzerland
// All rights reserved
//
// This file is part of OPAL.
//
// OPAL is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// You should have received a copy of the GNU General Public License
// along with OPAL. If not, see <https://www.gnu.org/licenses/>.
//
#include "BorisPusher.h"
#include "Physics/Units.h"
 
template <typename FieldFunction, typename... Arguments>
bool LF2<FieldFunction, Arguments...>::doAdvance_m(
    PartBunch_t* bunch, const size_t& i, const double& t, const double dt,
    Arguments&... args) const {
    bool flagNoDeletion = true;
 
    // push for first LF2 half step
    push_m(bunch->R(i), bunch->P(i), 0.5 * dt * Units::ns2s);
 
    flagNoDeletion = kick_m(bunch, i, t, dt * Units::ns2s, args...);
 
    // push for second LF2 half step
    push_m(bunch->R(i), bunch->P(i), 0.5 * dt * Units::ns2s);
 
    return flagNoDeletion;
}
 
template <typename FieldFunction, typename... Arguments>
void LF2<FieldFunction, Arguments...>::push_m(
    Vector_t<double, 3>& R, const Vector_t<double, 3>& P, const double& h) const {
    double const gamma          = sqrt(1.0 + dot(P, P));
    double const c_gamma        = Physics::c / gamma;
    Vector_t<double, 3> const v = P * c_gamma;
    R += h * v;
}
 
template <typename FieldFunction, typename... Arguments>
bool LF2<FieldFunction, Arguments...>::kick_m(
    PartBunch_t* bunch, const size_t& i, const double& t, const double& h,
    Arguments&... args) const {
    Vector_t<double, 3> externalE = Vector_t<double, 3>(0.0, 0.0, 0.0);
    Vector_t<double, 3> externalB = Vector_t<double, 3>(0.0, 0.0, 0.0);
 
    bool outOfBound = this->fieldfunc_m(t, i, externalE, externalB, args...);
 
    if (outOfBound)
        return false;
 
    double const q = 1;  // \todo  = bunch->Q(0) / Physics::q_e;
    double const M = 1;  // \todo  = bunch->M(0) * Units::GeV2eV;
                         // same rest energy
 
    BorisPusher pusher;
 
    // \todo pusher.kick(bunch->R(i), bunch->P(i), externalE, externalB, h, M, q);
 
    return true;
}