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#!/usr/bin/env python3
#
# --- Input file to test the saving of old particle positions
import numpy as np
from pywarpx import picmi
constants = picmi.constants
##########################
# numerics parameters
##########################
dt = 7.5e-10
# --- Nb time steps
max_steps = 10
# --- grid
nx = 64
nz = 64
xmin = 0
xmax = 0.03
zmin = 0
zmax = 0.03
##########################
# numerics components
##########################
grid = picmi.Cartesian2DGrid(
number_of_cells = [nx, nz],
lower_bound = [xmin, zmin],
upper_bound = [xmax, zmax],
lower_boundary_conditions = ['dirichlet', 'periodic'],
upper_boundary_conditions = ['dirichlet', 'periodic'],
lower_boundary_conditions_particles = ['absorbing', 'periodic'],
upper_boundary_conditions_particles = ['absorbing', 'periodic'],
moving_window_velocity = None,
warpx_max_grid_size = 32
)
solver = picmi.ElectrostaticSolver(
grid=grid, method='Multigrid', required_precision=1e-6,
warpx_self_fields_verbosity=0
)
##########################
# physics components
##########################
uniform_plasma_elec = picmi.UniformDistribution(
density = 1e15,
upper_bound = [None] * 3,
rms_velocity = [np.sqrt(constants.kb * 1e3 / constants.m_e)] * 3,
directed_velocity = [0.] * 3
)
electrons = picmi.Species(
particle_type='electron', name='electrons',
initial_distribution=uniform_plasma_elec,
warpx_save_previous_position=True
)
##########################
# diagnostics
##########################
field_diag = picmi.ParticleDiagnostic(
species=electrons,
name = 'diag1',
data_list=['previous_positions'],
period = 10,
write_dir = '.',
warpx_file_prefix = 'Python_prev_positions_plt'
)
##########################
# simulation setup
##########################
sim = picmi.Simulation(
solver = solver,
time_step_size = dt,
max_steps = max_steps,
verbose = 1
)
sim.add_species(
electrons,
layout = picmi.GriddedLayout(
n_macroparticle_per_cell=[1, 1], grid=grid
)
)
sim.add_diagnostic(field_diag)
##########################
# simulation run
##########################
sim.step(max_steps - 1)
##########################
# check that the new PIDs
# exist
##########################
assert (sim.extension.get_particle_comp_index('electrons', 'prev_x') > 0)
assert (sim.extension.get_particle_comp_index('electrons', 'prev_z') > 0)
prev_z_vals = sim.extension.get_particle_arrays(
'electrons', 'prev_z', 0
)
for z_vals in prev_z_vals:
assert np.all(z_vals < zmax)
##########################
# take the final sim step
##########################
sim.step(1)
|
