def check_fields(interp1_complex,
                 z,
                 r,
                 info_in_real_part,
                 z0,
                 gamma_b,
                 forward_propagating,
                 show_difference=False):
    """
    Check the real and imaginary part of the interpolation grid agree
    with the theory by:
    - Checking that the part (real or imaginary) that does not
        carry information is zero
    - Extracting the a0 from the other part and comparing it
        to the predicted value
    - Using the extracted value of a0 to compare the simulated
      profile with a gaussian profile
    """
    # Extract the part that has information
    if info_in_real_part:
        interp1 = interp1_complex.real
        zero_part = interp1_complex.imag
    else:
        interp1 = interp1_complex.imag
        zero_part = interp1_complex.real

    # Control that the part that has no information is 0
    assert np.allclose(0., zero_part, atol=1.e-6 * interp1.max())

    # Get the predicted properties of the laser in the boosted frame
    if gamma_b is None:
        boost = BoostConverter(1.)
    else:
        boost = BoostConverter(gamma_b)
    ctau_b, lambda0_b, Lprop_b, z0_b = \
        boost.copropag_length([ctau, 0.8e-6, Lprop, z0])
    # Take into account whether the pulse is propagating forward or backward
    if not forward_propagating:
        Lprop_b = -Lprop_b

    # Fit the on-axis profile to extract a0
    def fit_function(z, a0, z0_phase):
        return (gaussian_laser(z, r[0], a0, z0_phase, z0_b + Lprop_b, ctau_b,
                               lambda0_b))

    fit_result = curve_fit(fit_function,
                           z,
                           interp1[:, 0],
                           p0=np.array([a0, z0_b + Lprop_b]))
    a0_fit, z0_fit = fit_result[0]

    # Check that the a0 agrees within 5% of the predicted value
    assert abs(abs(a0_fit) - a0) / a0 < 0.05

    # Calculate predicted fields
    r2d, z2d = np.meshgrid(r, z)
    # Factor 0.5 due to the definition of the interpolation grid
    interp1_predicted = gaussian_laser(z2d, r2d, a0_fit, z0_fit,
                                       z0_b + Lprop_b, ctau_b, lambda0_b)
    # Plot the difference
    if show_difference:
        import matplotlib.pyplot as plt
        plt.subplot(311)
        plt.imshow(interp1.T)
        plt.colorbar()
        plt.subplot(312)
        plt.imshow(interp1_predicted.T)
        plt.colorbar()
        plt.subplot(313)
        plt.imshow((interp1_predicted - interp1).T)
        plt.colorbar()
        plt.show()
    # Control the values (with a precision of 3%)
    assert np.allclose(interp1_predicted, interp1, atol=3.e-2 * interp1.max())
Exemple #2
0
def run_simulation(gamma_boost, use_separate_electron_species):
    """
    Run a simulation with a laser pulse going through a gas jet of ionizable
    N5+ atoms, and check the fraction of atoms that are in the N5+ state.

    Parameters
    ----------
    gamma_boost: float
        The Lorentz factor of the frame in which the simulation is carried out.
    use_separate_electron_species: bool
        Whether to use separate electron species for each level, or
        a single electron species for all levels.
    """
    # The simulation box
    zmax_lab = 20.e-6  # Length of the box along z (meters)
    zmin_lab = 0.e-6
    Nr = 3  # Number of gridpoints along r
    rmax = 10.e-6  # Length of the box along r (meters)
    Nm = 2  # Number of modes used

    # The particles of the plasma
    p_zmin = 5.e-6  # Position of the beginning of the plasma (meters)
    p_zmax = 15.e-6
    p_rmin = 0.  # Minimal radial position of the plasma (meters)
    p_rmax = 100.e-6  # Maximal radial position of the plasma (meters)
    n_atoms = 0.2  # The atomic density is chosen very low,
    # to avoid collective effects
    p_nz = 2  # Number of particles per cell along z
    p_nr = 1  # Number of particles per cell along r
    p_nt = 4  # Number of particles per cell along theta

    # Boosted frame
    boost = BoostConverter(gamma_boost)
    # Boost the different quantities
    beta_boost = np.sqrt(1. - 1. / gamma_boost**2)
    zmin, zmax = boost.static_length([zmin_lab, zmax_lab])
    p_zmin, p_zmax = boost.static_length([p_zmin, p_zmax])
    n_atoms, = boost.static_density([n_atoms])
    # Increase the number of particles per cell in order to keep sufficient
    # statistics for the evaluation of the ionization fraction
    if gamma_boost > 1:
        p_nz = int(2 * gamma_boost * (1 + beta_boost) * p_nz)

    # The laser
    a0 = 1.8  # Laser amplitude
    lambda0_lab = 0.8e-6  # Laser wavelength
    # Boost the laser wavelength before calculating the laser amplitude
    lambda0, = boost.copropag_length([lambda0_lab], beta_object=1.)
    # Duration and initial position of the laser
    ctau = 10. * lambda0
    z0 = -2 * ctau
    # Calculate laser amplitude
    omega = 2 * np.pi * c / lambda0
    E0 = a0 * m_e * c * omega / e
    B0 = E0 / c

    def laser_func(F, x, y, z, t, amplitude, length_scale):
        """
        Function that describes a Gaussian laser with infinite waist
        """
        return( F + amplitude * math.cos( 2*np.pi*(z-c*t)/lambda0 ) * \
                math.exp( - (z - c*t - z0)**2/ctau**2 ) )

    # Resolution and number of timesteps
    dz = lambda0 / 16.
    dt = dz / c
    Nz = int((zmax - zmin) / dz) + 1
    N_step = int(
        (2. * 40. * lambda0 + zmax - zmin) / (dz * (1 + beta_boost))) + 1

    # Get the speed of the plasma
    uz_m, = boost.longitudinal_momentum([0.])
    v_plasma, = boost.velocity([0.])

    # The diagnostics
    diag_period = N_step - 1  # Period of the diagnostics in number of timesteps

    # Initial ionization level of the Nitrogen atoms
    level_start = 2
    # Initialize the simulation object, with the neutralizing electrons
    # No particles are created because we do not pass the density
    sim = Simulation(Nz,
                     zmax,
                     Nr,
                     rmax,
                     Nm,
                     dt,
                     zmin=zmin,
                     v_comoving=v_plasma,
                     use_galilean=False,
                     boundaries='open',
                     use_cuda=use_cuda)

    # Add the charge-neutralizing electrons
    elec = sim.add_new_species(q=-e,
                               m=m_e,
                               n=level_start * n_atoms,
                               p_nz=p_nz,
                               p_nr=p_nr,
                               p_nt=p_nt,
                               p_zmin=p_zmin,
                               p_zmax=p_zmax,
                               p_rmin=p_rmin,
                               p_rmax=p_rmax,
                               continuous_injection=False,
                               uz_m=uz_m)
    # Add the N atoms
    ions = sim.add_new_species(q=0,
                               m=14. * m_p,
                               n=n_atoms,
                               p_nz=p_nz,
                               p_nr=p_nr,
                               p_nt=p_nt,
                               p_zmin=p_zmin,
                               p_zmax=p_zmax,
                               p_rmin=p_rmin,
                               p_rmax=p_rmax,
                               continuous_injection=False,
                               uz_m=uz_m)
    # Add the target electrons
    if use_separate_electron_species:
        # Use a dictionary of electron species: one per ionizable level
        target_species = {}
        level_max = 6  # N can go up to N7+, but here we stop at N6+
        for i_level in range(level_start, level_max):
            target_species[i_level] = sim.add_new_species(q=-e, m=m_e)
    else:
        # Use the pre-existing, charge-neutralizing electrons
        target_species = elec
        level_max = None  # Default is going up to N7+
    # Define ionization
    ions.make_ionizable(element='N',
                        level_start=level_start,
                        level_max=level_max,
                        target_species=target_species)
    # Set the moving window
    sim.set_moving_window(v=v_plasma)

    # Add a laser to the fields of the simulation (external fields)
    sim.external_fields = [
        ExternalField(laser_func, 'Ex', E0, 0.),
        ExternalField(laser_func, 'By', B0, 0.)
    ]

    # Add a particle diagnostic
    sim.diags = [
        ParticleDiagnostic(
            diag_period,
            {"ions": ions},
            particle_data=["position", "gamma", "weighting", "E", "B"],
            # Test output of fields and gamma for standard
            # (non-boosted) particle diagnostics
            write_dir='tests/diags',
            comm=sim.comm)
    ]
    if gamma_boost > 1:
        T_sim_lab = (2. * 40. * lambda0_lab + zmax_lab - zmin_lab) / c
        sim.diags.append(
            BackTransformedParticleDiagnostic(zmin_lab,
                                              zmax_lab,
                                              v_lab=0.,
                                              dt_snapshots_lab=T_sim_lab / 2.,
                                              Ntot_snapshots_lab=3,
                                              gamma_boost=gamma_boost,
                                              period=diag_period,
                                              fldobject=sim.fld,
                                              species={"ions": ions},
                                              comm=sim.comm,
                                              write_dir='tests/lab_diags'))

    # Run the simulation
    sim.step(N_step, use_true_rho=True)

    # Check the fraction of N5+ ions at the end of the simulation
    w = ions.w
    ioniz_level = ions.ionizer.ionization_level
    # Get the total number of N atoms/ions (all ionization levels together)
    ntot = w.sum()
    # Get the total number of N5+ ions
    n_N5 = w[ioniz_level == 5].sum()
    # Get the fraction of N5+ ions, and check that it is close to 0.32
    N5_fraction = n_N5 / ntot
    print('N5+ fraction: %.4f' % N5_fraction)
    assert ((N5_fraction > 0.30) and (N5_fraction < 0.34))

    # When different electron species are created, check the fraction of
    # each electron species
    if use_separate_electron_species:
        for i_level in range(level_start, level_max):
            n_N = w[ioniz_level == i_level].sum()
            assert np.allclose(target_species[i_level].w.sum(), n_N)

    # Check consistency in the regular openPMD diagnostics
    ts = OpenPMDTimeSeries('./tests/diags/hdf5/')
    last_iteration = ts.iterations[-1]
    w, q = ts.get_particle(['w', 'charge'],
                           species="ions",
                           iteration=last_iteration)
    # Check that the openPMD file contains the same number of N5+ ions
    n_N5_openpmd = np.sum(w[(4.5 * e < q) & (q < 5.5 * e)])
    assert np.isclose(n_N5_openpmd, n_N5)
    # Remove openPMD files
    shutil.rmtree('./tests/diags/')

    # Check consistency of the back-transformed openPMD diagnostics
    if gamma_boost > 1.:
        ts = OpenPMDTimeSeries('./tests/lab_diags/hdf5/')
        last_iteration = ts.iterations[-1]
        w, q = ts.get_particle(['w', 'charge'],
                               species="ions",
                               iteration=last_iteration)
        # Check that the openPMD file contains the same number of N5+ ions
        n_N5_openpmd = np.sum(w[(4.5 * e < q) & (q < 5.5 * e)])
        assert np.isclose(n_N5_openpmd, n_N5)
        # Remove openPMD files
        shutil.rmtree('./tests/lab_diags/')
Exemple #3
0
    n = np.where(z >= ramp_up + plateau + ramp_down, 0, n)
    # Add transverse guiding parabolic profile
    n = n * (1. + rel_delta_n_over_w2 * r**2)
    return (n)


# The bunch
bunch_zmin = z0 - 10.e-6
bunch_zmax = bunch_zmin + 4.e-6
bunch_rmax = 10.e-6
bunch_gamma = 400.
bunch_n = 5.e23
# Convert parameters to boosted frame
bunch_beta = np.sqrt(1. - 1. / bunch_gamma**2)
bunch_zmin, bunch_zmax = \
    boost.copropag_length( [ bunch_zmin, bunch_zmax ], beta_object=bunch_beta )
bunch_n, = boost.copropag_density([bunch_n], beta_object=bunch_beta)
bunch_gamma, = boost.gamma([bunch_gamma])

# The moving window (moves with the group velocity in a plasma)
v_window = c * (1 - 0.5 * n_e / 1.75e27)
# Convert parameter to boosted frame
v_window, = boost.velocity([v_window])

# The diagnostics
diag_period = 50  # Period of the diagnostics in number of timesteps
# Whether to write the fields in the lab frame
Ntot_snapshot_lab = 20
dt_snapshot_lab = (zmax - zmin) / c
track_bunch = False  # Whether to tag and track the particles of the bunch
Exemple #4
0
def run_simulation(gamma_boost, show):
    """
    Run a simulation with a relativistic electron bunch crosses a laser

    Parameters
    ----------
    gamma_boost: float
        The Lorentz factor of the frame in which the simulation is carried out.
    show: bool
        Whether to show a plot of the angular distribution
    """
    # Boosted frame
    boost = BoostConverter(gamma_boost)

    # The simulation timestep
    diag_period = 100
    N_step = 101  # Number of iterations to perform
    # Calculate timestep to resolve the interaction with enough points
    laser_duration_boosted, = boost.copropag_length([laser_duration],
                                                    beta_object=-1)
    bunch_sigma_z_boosted, = boost.copropag_length([bunch_sigma_z],
                                                   beta_object=1)
    dt = (4 * laser_duration_boosted + bunch_sigma_z_boosted / c) / N_step

    # Initialize the simulation object
    zmax, zmin = boost.copropag_length([zmax_lab, zmin_lab], beta_object=1.)
    sim = Simulation(Nz,
                     zmax,
                     Nr,
                     rmax,
                     Nm,
                     dt,
                     p_zmin=0,
                     p_zmax=0,
                     p_rmin=0,
                     p_rmax=0,
                     p_nz=1,
                     p_nr=1,
                     p_nt=1,
                     n_e=1,
                     dens_func=None,
                     zmin=zmin,
                     boundaries='periodic',
                     use_cuda=use_cuda)
    # Remove particles that were previously created
    sim.ptcl = []
    print('Initialized simulation')

    # Add electron bunch (automatically converted to boosted-frame)
    add_elec_bunch_gaussian(sim,
                            sig_r=1.e-6,
                            sig_z=bunch_sigma_z,
                            n_emit=0.,
                            gamma0=gamma_bunch_mean,
                            sig_gamma=gamma_bunch_rms,
                            Q=Q_bunch,
                            N=N_bunch,
                            tf=0.0,
                            zf=0.5 * (zmax + zmin),
                            boost=boost)
    elec = sim.ptcl[0]
    print('Initialized electron bunch')
    # Add a photon species
    photons = Particles(q=0,
                        m=0,
                        n=0,
                        Npz=1,
                        zmin=0,
                        zmax=0,
                        Npr=1,
                        rmin=0,
                        rmax=0,
                        Nptheta=1,
                        dt=sim.dt,
                        ux_m=0.,
                        uy_m=0.,
                        uz_m=0.,
                        ux_th=0.,
                        uy_th=0.,
                        uz_th=0.,
                        dens_func=None,
                        continuous_injection=False,
                        grid_shape=sim.fld.interp[0].Ez.shape,
                        particle_shape='linear',
                        use_cuda=sim.use_cuda)
    sim.ptcl.append(photons)
    print('Initialized photons')

    # Activate Compton scattering for electrons of the bunch
    elec.activate_compton(target_species=photons,
                          laser_energy=laser_energy,
                          laser_wavelength=laser_wavelength,
                          laser_waist=laser_waist,
                          laser_ctau=laser_ctau,
                          laser_initial_z0=laser_initial_z0,
                          ratio_w_electron_photon=50,
                          boost=boost)
    print('Activated Compton')

    # Add diagnostics
    if write_hdf5:
        sim.diags = [
            ParticleDiagnostic(diag_period,
                               species={
                                   'electrons': elec,
                                   'photons': photons
                               },
                               comm=sim.comm)
        ]

    # Get initial total momentum
    initial_total_elec_px = (elec.w * elec.ux).sum() * m_e * c
    initial_total_elec_py = (elec.w * elec.uy).sum() * m_e * c
    initial_total_elec_pz = (elec.w * elec.uz).sum() * m_e * c

    ### Run the simulation
    for species in sim.ptcl:
        species.send_particles_to_gpu()

    for i_step in range(N_step):
        for species in sim.ptcl:
            species.halfpush_x()
        elec.handle_elementary_processes(sim.time + 0.5 * sim.dt)
        for species in sim.ptcl:
            species.halfpush_x()
        # Increment time and run diagnostics
        sim.time += sim.dt
        sim.iteration += 1
        for diag in sim.diags:
            diag.write(sim.iteration)
        # Print fraction of photons produced
        if i_step % 10 == 0:
            for species in sim.ptcl:
                species.receive_particles_from_gpu()
            simulated_frac = photons.w.sum() / elec.w.sum()
            for species in sim.ptcl:
                species.send_particles_to_gpu()
            print( 'Iteration %d: Photon fraction per electron = %f' \
                       %(i_step, simulated_frac) )

    for species in sim.ptcl:
        species.receive_particles_from_gpu()

    # Check estimation of photon fraction
    check_photon_fraction(simulated_frac)
    # Check conservation of momentum (is only conserved )
    if elec.compton_scatterer.ratio_w_electron_photon == 1:
        check_momentum_conservation(gamma_boost, photons, elec,
                                    initial_total_elec_px,
                                    initial_total_elec_py,
                                    initial_total_elec_pz)

    # Transform the photon momenta back into the lab frame
    photon_u = 1. / photons.inv_gamma
    photon_lab_pz = boost.gamma0 * (photons.uz + boost.beta0 * photon_u)
    photon_lab_p = boost.gamma0 * (photon_u + boost.beta0 * photons.uz)

    # Plot the scaled angle and frequency
    if show:
        import matplotlib.pyplot as plt
        # Bin the photons on a grid in frequency and angle
        freq_min = 0.5
        freq_max = 1.2
        N_freq = 500
        gammatheta_min = 0.
        gammatheta_max = 1.
        N_gammatheta = 100
        hist_range = [[freq_min, freq_max], [gammatheta_min, gammatheta_max]]
        extent = [freq_min, freq_max, gammatheta_min, gammatheta_max]
        fundamental_frequency = 4 * gamma_bunch_mean**2 * c / laser_wavelength
        photon_scaled_freq = photon_lab_p * c / (h * fundamental_frequency)
        gamma_theta = gamma_bunch_mean * np.arccos(
            photon_lab_pz / photon_lab_p)
        grid, freq_bins, gammatheta_bins = np.histogram2d(
            photon_scaled_freq,
            gamma_theta,
            weights=photons.w,
            range=hist_range,
            bins=[N_freq, N_gammatheta])
        # Normalize by solid angle, frequency and number of photons
        dw = (freq_bins[1] - freq_bins[0]) * 2 * np.pi * fundamental_frequency
        dtheta = (gammatheta_bins[1] - gammatheta_bins[0]) / gamma_bunch_mean
        domega = 2. * np.pi * np.sin(
            gammatheta_bins / gamma_bunch_mean) * dtheta
        grid /= dw * domega[np.newaxis, 1:] * elec.w.sum()
        grid = np.where(grid == 0, np.nan, grid)
        plt.imshow(grid.T,
                   origin='lower',
                   extent=extent,
                   cmap='gist_earth',
                   aspect='auto',
                   vmax=1.8e-16)
        plt.title('Particles, $d^2N/d\omega \,d\Omega$')
        plt.xlabel('Scaled energy ($\omega/4\gamma^2\omega_\ell$)')
        plt.ylabel(r'$\gamma \theta$')
        plt.colorbar()
        # Plot theory
        plt.plot(1. / (1 + gammatheta_bins**2), gammatheta_bins, color='r')
        plt.show()
        plt.clf()
# Create empty arrays for saving rms bunch sizes
sig_zp = np.zeros(int(N_step / N_show) + 1)
sig_xp = np.zeros(int(N_step / N_show) + 1)
sig_yp = np.zeros(int(N_step / N_show) + 1)

# Set initial bunch sizes
sig_zp[0] = np.std(sim.ptcl[0].z)
sig_xp[0] = np.std(sim.ptcl[0].x)
sig_yp[0] = np.std(sim.ptcl[0].y)

# Create array corresponding to the propagation distance of the bunch
z_prop = np.arange(int(N_step / N_show) + 1) * ((zmax - zmin) / Nz) * N_show
z_prop += -20.e-6
if l_boost:
    z_prop, = boost.copropag_length([z_prop], beta_object=boost.beta0)

# Carry out the simulation
for k in range(int(N_step / N_show)):
    sim.step(N_show)
    sig_zp[k + 1] = np.std(sim.ptcl[0].z)
    sig_xp[k + 1] = np.std(sim.ptcl[0].x)
    sig_yp[k + 1] = np.std(sim.ptcl[0].y)
    if show_fields:
        # Show the fields
        plt.figure(0)
        plt.clf()
        sim.fld.interp[0].show('Ez')
        plt.figure(1)
        plt.clf()
        sim.fld.interp[0].show('Er')
Exemple #6
0
def run_simulation(gamma_boost):
    """
    Run a simulation with a laser pulse going through a gas jet of ionizable
    N5+ atoms, and check the fraction of atoms that are in the N5+ state.

    Parameters
    ----------
    gamma_boost: float
        The Lorentz factor of the frame in which the simulation is carried out.
    """
    # The simulation box
    zmax_lab = 20.e-6  # Length of the box along z (meters)
    zmin_lab = 0.e-6
    Nr = 3  # Number of gridpoints along r
    rmax = 10.e-6  # Length of the box along r (meters)
    Nm = 2  # Number of modes used

    # The particles of the plasma
    p_zmin = 5.e-6  # Position of the beginning of the plasma (meters)
    p_zmax = 15.e-6
    p_rmin = 0.  # Minimal radial position of the plasma (meters)
    p_rmax = 100.e-6  # Maximal radial position of the plasma (meters)
    n_e = 1.  # The plasma density is chosen very low,
    # to avoid collective effects
    p_nz = 2  # Number of particles per cell along z
    p_nr = 1  # Number of particles per cell along r
    p_nt = 4  # Number of particles per cell along theta

    # Boosted frame
    boost = BoostConverter(gamma_boost)
    # Boost the different quantities
    beta_boost = np.sqrt(1. - 1. / gamma_boost**2)
    zmin, zmax = boost.static_length([zmin_lab, zmax_lab])
    p_zmin, p_zmax = boost.static_length([p_zmin, p_zmax])
    n_e, = boost.static_density([n_e])
    # Increase the number of particles per cell in order to keep sufficient
    # statistics for the evaluation of the ionization fraction
    if gamma_boost > 1:
        p_nz = int(2 * gamma_boost * (1 + beta_boost) * p_nz)

    # The laser
    a0 = 1.8  # Laser amplitude
    lambda0_lab = 0.8e-6  # Laser wavelength
    # Boost the laser wavelength before calculating the laser amplitude
    lambda0, = boost.copropag_length([lambda0_lab], beta_object=1.)
    # Duration and initial position of the laser
    ctau = 10. * lambda0
    z0 = -2 * ctau
    # Calculate laser amplitude
    omega = 2 * np.pi * c / lambda0
    E0 = a0 * m_e * c * omega / e
    B0 = E0 / c

    def laser_func(F, x, y, z, t, amplitude, length_scale):
        """
        Function that describes a Gaussian laser with infinite waist
        """
        return( F + amplitude * math.cos( 2*np.pi*(z-c*t)/lambda0 ) * \
                math.exp( - (z - c*t - z0)**2/ctau**2 ) )

    # Resolution and number of timesteps
    dz = lambda0 / 16.
    dt = dz / c
    Nz = int((zmax - zmin) / dz) + 1
    N_step = int(
        (2. * 40. * lambda0 + zmax - zmin) / (dz * (1 + beta_boost))) + 1

    # Get the speed of the plasma
    uz_m, = boost.longitudinal_momentum([0.])
    v_plasma, = boost.velocity([0.])

    # The diagnostics
    diag_period = N_step - 1  # Period of the diagnostics in number of timesteps

    # Initialize the simulation object
    sim = Simulation(
        Nz,
        zmax,
        Nr,
        rmax,
        Nm,
        dt,
        p_zmax,
        p_zmax,  # No electrons get created because we pass p_zmin=p_zmax
        p_rmin,
        p_rmax,
        p_nz,
        p_nr,
        p_nt,
        n_e,
        zmin=zmin,
        initialize_ions=False,
        v_comoving=v_plasma,
        use_galilean=False,
        boundaries='open',
        use_cuda=use_cuda)
    sim.set_moving_window(v=v_plasma)

    # Add the N atoms
    p_zmin, p_zmax, Npz = adapt_to_grid(sim.fld.interp[0].z, p_zmin, p_zmax,
                                        p_nz)
    p_rmin, p_rmax, Npr = adapt_to_grid(sim.fld.interp[0].r, p_rmin, p_rmax,
                                        p_nr)
    sim.ptcl.append(
        Particles(q=e,
                  m=14. * m_p,
                  n=0.2 * n_e,
                  Npz=Npz,
                  zmin=p_zmin,
                  zmax=p_zmax,
                  Npr=Npr,
                  rmin=p_rmin,
                  rmax=p_rmax,
                  Nptheta=p_nt,
                  dt=dt,
                  use_cuda=use_cuda,
                  uz_m=uz_m,
                  grid_shape=sim.fld.interp[0].Ez.shape,
                  continuous_injection=False))
    sim.ptcl[1].make_ionizable(element='N',
                               level_start=0,
                               target_species=sim.ptcl[0])

    # Add a laser to the fields of the simulation (external fields)
    sim.external_fields = [
        ExternalField(laser_func, 'Ex', E0, 0.),
        ExternalField(laser_func, 'By', B0, 0.)
    ]

    # Add a field diagnostic
    sim.diags = [
        ParticleDiagnostic(diag_period, {"ions": sim.ptcl[1]},
                           write_dir='tests/diags',
                           comm=sim.comm)
    ]
    if gamma_boost > 1:
        T_sim_lab = (2. * 40. * lambda0_lab + zmax_lab - zmin_lab) / c
        sim.diags.append(
            BoostedParticleDiagnostic(zmin_lab,
                                      zmax_lab,
                                      v_lab=0.,
                                      dt_snapshots_lab=T_sim_lab / 2.,
                                      Ntot_snapshots_lab=3,
                                      gamma_boost=gamma_boost,
                                      period=diag_period,
                                      fldobject=sim.fld,
                                      species={"ions": sim.ptcl[1]},
                                      comm=sim.comm,
                                      write_dir='tests/lab_diags'))

    # Run the simulation
    sim.step(N_step, use_true_rho=True)

    # Check the fraction of N5+ ions at the end of the simulation
    w = sim.ptcl[1].w
    ioniz_level = sim.ptcl[1].ionizer.ionization_level
    # Get the total number of N atoms/ions (all ionization levels together)
    ntot = w.sum()
    # Get the total number of N5+ ions
    n_N5 = w[ioniz_level == 5].sum()
    # Get the fraction of N5+ ions, and check that it is close to 0.32
    N5_fraction = n_N5 / ntot
    print('N5+ fraction: %.4f' % N5_fraction)
    assert ((N5_fraction > 0.30) and (N5_fraction < 0.34))

    # Check consistency in the regular openPMD diagnostics
    ts = OpenPMDTimeSeries('./tests/diags/hdf5/')
    last_iteration = ts.iterations[-1]
    w, q = ts.get_particle(['w', 'charge'],
                           species="ions",
                           iteration=last_iteration)
    # Check that the openPMD file contains the same number of N5+ ions
    n_N5_openpmd = np.sum(w[(4.5 * e < q) & (q < 5.5 * e)])
    assert np.isclose(n_N5_openpmd, n_N5)
    # Remove openPMD files
    shutil.rmtree('./tests/diags/')

    # Check consistency of the back-transformed openPMD diagnostics
    if gamma_boost > 1.:
        ts = OpenPMDTimeSeries('./tests/lab_diags/hdf5/')
        last_iteration = ts.iterations[-1]
        w, q = ts.get_particle(['w', 'charge'],
                               species="ions",
                               iteration=last_iteration)
        # Check that the openPMD file contains the same number of N5+ ions
        n_N5_openpmd = np.sum(w[(4.5 * e < q) & (q < 5.5 * e)])
        assert np.isclose(n_N5_openpmd, n_N5)
        # Remove openPMD files
        shutil.rmtree('./tests/lab_diags/')