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Reference Particle: Store Charge & Mass #229

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Aug 31, 2022
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Reference Particle: Store Charge & Mass #229

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7ee5a38
Reference Particle: Store Charge & Mass
ax3l Aug 31, 2022
399608a
Update Examples
ax3l Aug 31, 2022
0dd09fd
Update Docs
ax3l Aug 31, 2022
cb56292
Fix: Python Reference Lifetime
ax3l Aug 31, 2022
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18 changes: 15 additions & 3 deletions docs/source/usage/python.rst
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Expand Up @@ -63,13 +63,13 @@ General

This must come first, before particle beams and lattice elements are initialized.

.. py:method:: add_particles(qm_qeeV, charge_C, distr, npart)
.. py:method:: add_particles(charge_C, distr, npart)

Generate and add n particles to the particle container.
Note: Set the reference particle properties (charge, mass, energy) first.

Will also resize the geometry based on the updated particle distribution's extent and then redistribute particles in according AMReX grid boxes.

:param float qm_qeeV: charge/mass ratio (q_e/eV)
:param float charge_C: bunch charge (C)
:param distr: distribution function to draw from (object from :py:mod:`impactx.distribution`)
:param int npart: number of particles to draw
Expand Down Expand Up @@ -224,7 +224,19 @@ Particles

Read-only: Get reference particle beta*gamma

.. py:method:: set_energy_MeV(energy_MeV, massE_MeV)
.. py:property:: qm_qeeV

Read-only: Get reference particle charge to mass ratio (elementary charge/eV)

.. py:method:: set_charge_qe(charge_qe)

Write-only: Set reference particle charge in (positive) elementary charges.

.. py:method:: set_mass_MeV(massE)

Write-only: Set reference particle rest mass (MeV/c^2).

.. py:method:: set_energy_MeV(energy_MeV)

Write-only: Set reference particle energy.

Expand Down
14 changes: 7 additions & 7 deletions examples/chicane/run_chicane.py
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Expand Up @@ -23,11 +23,14 @@
# load a 5 GeV electron beam with an initial
# normalized transverse rms emittance of 1 um
energy_MeV = 5.0e3 # reference energy
charge_C = 1.0e-9 # used with space charge
mass_MeV = 0.510998950
qm_qeeV = -1.0e-6 / mass_MeV # charge/mass
bunch_charge_C = 1.0e-9 # used with space charge
npart = 10000 # number of macro particles

# reference particle
ref = sim.particle_container().ref_particle()
ref.set_charge_qe(-1.0).set_mass_MeV(0.510998950).set_energy_MeV(energy_MeV)

# particle bunch
distr = distribution.Waterbag(
sigmaX=2.2951017632e-5,
sigmaY=1.3084093142e-5,
Expand All @@ -39,10 +42,7 @@
muypy=0.933345606203060,
mutpt=0.999999961419755,
)
sim.add_particles(qm_qeeV, charge_C, distr, npart)

# set the energy in the reference particle
sim.particle_container().ref_particle().set_energy_MeV(energy_MeV, mass_MeV)
sim.add_particles(bunch_charge_C, distr, npart)

# design the accelerator lattice
ns = 25 # number of slices per ds in the element
Expand Down
14 changes: 7 additions & 7 deletions examples/fodo/run_fodo.py
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Expand Up @@ -23,11 +23,14 @@
# load a 2 GeV electron beam with an initial
# unnormalized rms emittance of 2 nm
energy_MeV = 2.0e3 # reference energy
charge_C = 1.0e-9 # used with space charge
mass_MeV = 0.510998950
qm_qeeV = -1.0e-6 / mass_MeV # charge/mass
bunch_charge_C = 1.0e-9 # used with space charge
npart = 10000 # number of macro particles

# reference particle
ref = sim.particle_container().ref_particle()
ref.set_charge_qe(-1.0).set_mass_MeV(0.510998950).set_energy_MeV(energy_MeV)

# particle bunch
distr = distribution.Waterbag(
sigmaX=3.9984884770e-5,
sigmaY=3.9984884770e-5,
Expand All @@ -39,10 +42,7 @@
muypy=0.846574929020762,
mutpt=0.0,
)
sim.add_particles(qm_qeeV, charge_C, distr, npart)

# set the energy in the reference particle
sim.particle_container().ref_particle().set_energy_MeV(energy_MeV, mass_MeV)
sim.add_particles(bunch_charge_C, distr, npart)

# design the accelerator lattice
ns = 25 # number of slices per ds in the element
Expand Down
14 changes: 7 additions & 7 deletions examples/iota_lattice/run_iotalattice.py
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Expand Up @@ -22,11 +22,14 @@

# init particle beam
energy_MeV = 2.5
charge_C = 1.0e-9 # assign zero weighting to particles
mass_MeV = 938.27208816
qm_qeeV = 1.0e-6 / mass_MeV
bunch_charge_C = 1.0e-9 # used with space charge
npart = 10000

# reference particle
ref = sim.particle_container().ref_particle()
ref.set_charge_qe(1.0).set_mass_MeV(938.27208816).set_energy_MeV(energy_MeV)

# particle bunch
distr = distribution.Waterbag(
sigmaX=1.588960728035e-3,
sigmaY=2.496625268437e-3,
Expand All @@ -35,10 +38,7 @@
sigmaPy=1.802433091137e-3,
sigmaPt=0.0,
)
sim.add_particles(qm_qeeV, charge_C, distr, npart)

# set the energy in the reference particle
sim.particle_container().ref_particle().set_energy_MeV(energy_MeV, mass_MeV)
sim.add_particles(bunch_charge_C, distr, npart)

# init accelerator lattice
ns = 10 # number of slices per ds in the element
Expand Down
17 changes: 7 additions & 10 deletions examples/iota_lens/run_iotalens.py
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Expand Up @@ -22,26 +22,23 @@

# load a 2.5 MeV proton beam
energy_MeV = 2.5 # reference energy
charge_C = 1.0e-9 # used with space charge
mass_MeV = 938.27208816
qm_qeeV = 1.0e-6 / mass_MeV # charge/mass
bunch_charge_C = 1.0e-9 # used with space charge
npart = 10000 # number of macro particles

# reference particle
ref = sim.particle_container().ref_particle()
ref.set_charge_qe(1.0).set_mass_MeV(938.27208816).set_energy_MeV(energy_MeV)

# particle bunch
distr = distribution.Waterbag(
sigmaX=2.0e-3,
sigmaY=2.0e-3,
sigmaT=1.0e-3,
sigmaPx=3.0e-4,
sigmaPy=3.0e-4,
sigmaPt=0.0,
muxpx=0.0,
muypy=0.0,
mutpt=0.0,
)
sim.add_particles(qm_qeeV, charge_C, distr, npart)

# set the energy in the reference particle
sim.particle_container().ref_particle().set_energy_MeV(energy_MeV, mass_MeV)
sim.add_particles(bunch_charge_C, distr, npart)

constEnd = elements.ConstF(ds=0.0025, kx=1.0, ky=1.0, kt=1.0e-12)
nllens = elements.NonlinearLens(knll=2.0e-7, cnll=0.01)
Expand Down
17 changes: 7 additions & 10 deletions examples/kurth/run_kurth.py
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Expand Up @@ -24,26 +24,23 @@
# unnormalized rms emittance of 1 um in each
# coordinate plane
energy_MeV = 2.0e3 # reference energy
charge_C = 1.0e-9 # used with space charge
mass_MeV = 938.27208816
qm_qeeV = 1.0e-6 / mass_MeV # charge/mass
bunch_charge_C = 1.0e-9 # used with space charge
npart = 10000 # number of macro particles

# reference particle
ref = sim.particle_container().ref_particle()
ref.set_charge_qe(1.0).set_mass_MeV(938.27208816).set_energy_MeV(energy_MeV)

# particle bunch
distr = distribution.Kurth6D(
sigmaX=1.0e-3,
sigmaY=1.0e-3,
sigmaT=3.369701494258956e-4,
sigmaPx=1.0e-3,
sigmaPy=1.0e-3,
sigmaPt=2.9676219145931020e-3,
muxpx=0.0,
muypy=0.0,
mutpt=0.0,
)
sim.add_particles(qm_qeeV, charge_C, distr, npart)

# set the energy in the reference particle
sim.particle_container().ref_particle().set_energy_MeV(energy_MeV, mass_MeV)
sim.add_particles(bunch_charge_C, distr, npart)

# design the accelerator lattice: here we just assign a single element
sim.lattice.append(elements.ConstF(ds=2.0, kx=1.0, ky=1.0, kt=1.0))
Expand Down
14 changes: 7 additions & 7 deletions examples/multipole/run_multipole.py
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Expand Up @@ -23,11 +23,14 @@
# load a 2 GeV electron beam with an initial
# unnormalized rms emittance of nm
energy_MeV = 2.0e3 # reference energy
charge_C = 1.0e-9 # used without space charge
mass_MeV = 0.510998950
qm_qeeV = -1.0e-6 / mass_MeV # charge/mass
bunch_charge_C = 1.0e-9 # used without space charge
npart = 10000 # number of macro particles

# reference particle
ref = sim.particle_container().ref_particle()
ref.set_charge_qe(-1.0).set_mass_MeV(0.510998950).set_energy_MeV(energy_MeV)

# particle bunch
distr = distribution.Waterbag(
sigmaX=4.0e-3,
sigmaY=4.0e-3,
Expand All @@ -36,10 +39,7 @@
sigmaPy=3.0e-4,
sigmaPt=2.0e-3,
)
sim.add_particles(qm_qeeV, charge_C, distr, npart)

# set the energy in the reference particle
sim.particle_container().ref_particle().set_energy_MeV(energy_MeV, mass_MeV)
sim.add_particles(bunch_charge_C, distr, npart)

# design the accelerator lattice
multipole = [
Expand Down
2 changes: 0 additions & 2 deletions src/ImpactX.H
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Expand Up @@ -71,14 +71,12 @@ namespace impactx
* distribution's extent and then redistribute particles in according
* AMReX grid boxes.
*
* @param qm charge/mass ratio (q_e/eV)
* @param bunch_charge bunch charge (C)
* @param distr distribution function to draw from (object)
* @param npart number of particles to draw
*/
void
add_particles (
amrex::ParticleReal qm,
amrex::ParticleReal bunch_charge,
distribution::KnownDistributions distr,
int npart
Expand Down
55 changes: 29 additions & 26 deletions src/initialization/InitDistribution.cpp
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Expand Up @@ -24,14 +24,21 @@ namespace impactx
{
void
ImpactX::add_particles (
amrex::ParticleReal qm,
amrex::ParticleReal bunch_charge,
distribution::KnownDistributions distr,
int npart
)
{
BL_PROFILE("ImpactX::add_particles");

auto const & ref = m_particle_container->GetRefParticle();
AMREX_ASSERT_WITH_MESSAGE(ref.charge_qe() != 0.0,
"add_particles: Reference particle charge not yet set!");
AMREX_ASSERT_WITH_MESSAGE(ref.mass_MeV() != 0.0,
"add_particles: Reference particle mass not yet set!");
AMREX_ASSERT_WITH_MESSAGE(ref.energy_MeV() != 0.0,
"add_particles: Reference particle energy not yet set!");

amrex::Vector<amrex::ParticleReal> x, y, t;
amrex::Vector<amrex::ParticleReal> px, py, pt;
amrex::ParticleReal ix, iy, it, ipx, ipy, ipt;
Expand Down Expand Up @@ -70,7 +77,8 @@ namespace impactx

int const lev = 0;
m_particle_container->AddNParticles(lev, x, y, t, px, py, pt,
qm, bunch_charge * rel_part_this_proc);
ref.qm_qeeV(),
bunch_charge * rel_part_this_proc);

// Resize the mesh to fit the spatial extent of the beam and then
// redistribute particles, so they reside on the MPI rank that is
Expand All @@ -97,16 +105,24 @@ namespace impactx
std::string particle_type; // Particle type
pp_dist.get("particle", particle_type);

amrex::ParticleReal qm = 0.0; // charge/mass ratio (q_e/eV)
amrex::ParticleReal qe; // charge (elementary charge)
amrex::ParticleReal massE; // MeV/c^2
if(particle_type == "electron") {
qm = -1.0/0.510998950e6;
qe = -1.0;
massE = 0.510998950;
} else if(particle_type == "proton") {
qm = 1.0/938.27208816e6;
qe = 1.0;
massE = 938.27208816;
}
else {
qm = 0.0;
else { // default to electron
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Wouldn't I be able to set up muons, for instance, if I provided a name and qe and massE for them?

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yes, we did not add that case yet but could issue a warning, for instance.

qe = -1.0;
massE = 0.510998950;
}

// set charge and mass and energy of ref particle
m_particle_container->GetRefParticle()
.set_charge_qe(qe).set_mass_MeV(massE).set_energy_MeV(energy);

int npart = 1; // Number of simulation particles
pp_dist.get("npart", npart);

Expand Down Expand Up @@ -134,7 +150,7 @@ namespace impactx
sigpx, sigpy, sigpt,
muxpx, muypy, mutpt));

add_particles(qm, bunch_charge, waterbag, npart);
add_particles(bunch_charge, waterbag, npart);

} else if (distribution_type == "kurth6d") {
amrex::ParticleReal sigx,sigy,sigt,sigpx,sigpy,sigpt;
Expand All @@ -154,7 +170,7 @@ namespace impactx
sigpx, sigpy, sigpt,
muxpx, muypy, mutpt));

add_particles(qm, bunch_charge, kurth6D, npart);
add_particles(bunch_charge, kurth6D, npart);

} else if (distribution_type == "gaussian") {
amrex::ParticleReal sigx,sigy,sigt,sigpx,sigpy,sigpt;
Expand All @@ -174,7 +190,7 @@ namespace impactx
sigpx, sigpy, sigpt,
muxpx, muypy, mutpt));

add_particles(qm, bunch_charge, gaussian, npart);
add_particles(bunch_charge, gaussian, npart);

} else if (distribution_type == "kvdist") {
amrex::ParticleReal sigx,sigy,sigt,sigpx,sigpy,sigpt;
Expand All @@ -194,7 +210,7 @@ namespace impactx
sigpx, sigpy, sigpt,
muxpx, muypy, mutpt));

add_particles(qm, bunch_charge, kvDist, npart);
add_particles(bunch_charge, kvDist, npart);

} else if (distribution_type == "kurth4d") {
amrex::ParticleReal sigx,sigy,sigt,sigpx,sigpy,sigpt;
Expand All @@ -214,7 +230,7 @@ namespace impactx
sigpx, sigpy, sigpt,
muxpx, muypy, mutpt));

add_particles(qm, bunch_charge, kurth4D, npart);
add_particles(bunch_charge, kurth4D, npart);
} else if (distribution_type == "semigaussian") {
amrex::ParticleReal sigx,sigy,sigt,sigpx,sigpy,sigpt;
amrex::ParticleReal muxpx = 0.0, muypy = 0.0, mutpt = 0.0;
Expand All @@ -233,24 +249,11 @@ namespace impactx
sigpx, sigpy, sigpt,
muxpx, muypy, mutpt));

add_particles(qm, bunch_charge, semigaussian, npart);
add_particles(bunch_charge, semigaussian, npart);
} else {
amrex::Abort("Unknown distribution: " + distribution_type);
}

// reference particle
amrex::ParticleReal massE; // MeV
if (particle_type == "electron") {
massE = 0.510998950;
} else if (particle_type == "proton") {
massE = 938.27208816;
} else {
massE = 0.510998950; // default to electron
}

// set the energy in the reference particle
m_particle_container->GetRefParticle().set_energy_MeV(energy, massE);

// print information on the initialized beam
amrex::Print() << "Beam kinetic energy (MeV): " << energy << std::endl;
amrex::Print() << "Bunch charge (C): " << bunch_charge << std::endl;
Expand Down
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