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Rigid injection: Center field scaling around the v push #5389

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Merged
merged 11 commits into from
Nov 1, 2024
Merged

Rigid injection: Center field scaling around the v push #5389

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5432633
Center field scaling around v push
RemiLehe Oct 1, 2024
fc58555
Merge branch 'development' into scale_rigid_injection
RemiLehe Oct 11, 2024
c58a7ac
Rely on rigid injection for injection into the undulator
RemiLehe Oct 1, 2024
f752b9a
Use rigid advance
RemiLehe Oct 1, 2024
08a25ad
Merge branch 'development' into scale_rigid_injection
RemiLehe Oct 31, 2024
0fb2a2c
Add more comments
RemiLehe Oct 31, 2024
7f405bd
Revert changes in the tests
RemiLehe Oct 31, 2024
959a918
Update checksum benchmarks
RemiLehe Oct 31, 2024
340da16
Update checksums
RemiLehe Oct 31, 2024
f6e4566
Clean-up: remove saving of optical depth and u
RemiLehe Oct 31, 2024
a6d786e
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RemiLehe Nov 1, 2024
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4 changes: 1 addition & 3 deletions Examples/Physics_applications/free_electron_laser/inputs_test_1d_fel
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Original file line number Diff line number Diff line change
Expand Up @@ -62,7 +62,6 @@ electrons.uz = gamma_bunch
electrons.zmax = -25e-6
electrons.zmin = -125e-6
electrons.zinject_plane=0.0
electrons.rigid_advance=0

positrons.charge = q_e
positrons.injection_style = nuniformpercell
Expand All @@ -77,7 +76,6 @@ positrons.uz = gamma_bunch
positrons.zmax = -25e-6
positrons.zmin = -125e-6
positrons.zinject_plane=0.0
positrons.rigid_advance=0

warpx.do_moving_window = 1
warpx.moving_window_dir = z
Expand All @@ -86,7 +84,7 @@ warpx.moving_window_v = sqrt(1-(1+K*K/2)/(gamma_bunch*gamma_bunch))
# Undulator field
particles.B_ext_particle_init_style = parse_B_ext_particle_function
particles.Bx_external_particle_function(x,y,z,t) = 0
particles.By_external_particle_function(x,y,z,t) = if( z>0, Bu*cos(k_u*z), 0 )
particles.By_external_particle_function(x,y,z,t) = Bu*cos(k_u*z)
particles.Bz_external_particle_function(x,y,z,t) =0.0

warpx.cfl = 0.99
7 changes: 5 additions & 2 deletions Source/Particles/Gather/ScaleFields.H
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Expand Up @@ -47,8 +47,11 @@ struct ScaleFields
// This only approximates what should be happening. The particles
// should by advanced a fraction of a time step instead.
// Scaling the fields is much easier and may be good enough.
const amrex::Real dtscale = 1._rt - (m_z_plane_previous - zp)/(m_vz_ave_boosted + m_v_boost)/m_dt;
if (0._rt < dtscale && dtscale < 1._rt)
amrex::Real dtscale = 0.5_rt - (m_z_plane_previous - zp)/(m_vz_ave_boosted + m_v_boost)/m_dt;
if (dtscale < 0._rt) {
dtscale = 0;
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@dpgrote dpgrote Oct 31, 2024

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Perhaps add a comment that since the scale factor is zero, the push of the velocity doesn't change the velocity.

}
if (dtscale < 1._rt)
{
Exp *= dtscale;
Eyp *= dtscale;
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6 changes: 0 additions & 6 deletions Source/Particles/RigidInjectedParticleContainer.cpp
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Expand Up @@ -252,9 +252,6 @@ RigidInjectedParticleContainer::PushPX (WarpXParIter& pti,
amrex::ParticleReal* AMREX_RESTRICT x_save = xp_save.dataPtr();
amrex::ParticleReal* AMREX_RESTRICT y_save = yp_save.dataPtr();
amrex::ParticleReal* AMREX_RESTRICT z_save = zp_save.dataPtr();
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@RemiLehe RemiLehe Oct 31, 2024

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Saving and re-setting u to its original value is not needed anymore since the scaling factor for E and B is 0 for particles to the left of the plane.

amrex::ParticleReal* AMREX_RESTRICT ux_save = uxp_save.dataPtr();
amrex::ParticleReal* AMREX_RESTRICT uy_save = uyp_save.dataPtr();
amrex::ParticleReal* AMREX_RESTRICT uz_save = uzp_save.dataPtr();

// Undo the push for particles not injected yet.
// The zp are advanced a fixed amount.
Expand All @@ -267,9 +264,6 @@ RigidInjectedParticleContainer::PushPX (WarpXParIter& pti,
amrex::ParticleReal xp, yp, zp;
GetPosition(i, xp, yp, zp);
if (zp <= z_plane_lev) {
ux[i] = ux_save[i];
uy[i] = uy_save[i];
uz[i] = uz_save[i];
xp = x_save[i];
yp = y_save[i];
if (rigid) {
Expand Down