# Two-stream instability warm-up: a 1D electrostatic PIC problem, used here
# as a quick, cheap first run before the heavier LWFA and beamline stages of
# this tutorial. Two cold-ish electron populations drift through each other
# at +/-beta0*c; the counter-streaming free energy grows an electrostatic
# wave until the beams trap each other and saturate.
#
# All parameters below are fixed (unlike the companion "A Two-stream
# Instability" episode, where you choose them yourself) so this runs in a
# few seconds and gets everyone to a working WarpX + Python + Jupyter
# pipeline before the LWFA stage.

####################
### MY CONSTANTS ###
####################
# PLASMA
my_constants.n0 = 1.e17          # electron density of each beam [m^-3]
my_constants.T0 = 5.*q_e         # thermal energy of each beam [J], from 5 eV
my_constants.v_te = sqrt(T0 / m_e)
my_constants.beta0 = 0.1         # drift velocity of each beam, in units of c
my_constants.omega_pe = sqrt(n0*q_e**2/(m_e*epsilon0))

# BOX: sized to fit ~16 wavelengths of the fastest-growing mode,
# lambda ~ 2*pi*beta0*(c/omega_pe)
my_constants.Lx = 10.*clight/omega_pe
my_constants.nx = 256
my_constants.dx = Lx/nx

# TIME: long enough for the instability to grow and saturate
my_constants.cfl = 0.9
my_constants.T = 100./omega_pe
my_constants.dt = cfl * dx / clight
my_constants.nt = floor(T/dt)

##########################
### GENERAL PARAMETERS ###
##########################
stop_time = T
amr.n_cell = nx nx nx
amr.max_level = 0
geometry.dims = 1
geometry.prob_lo = -0.5*Lx -0.5*Lx  -0.5*Lx
geometry.prob_hi =  0.5*Lx  0.5*Lx   0.5*Lx

##########################
### BOUNDARY CONDITION ###
##########################
boundary.field_lo = periodic periodic periodic
boundary.field_hi = periodic periodic periodic
boundary.particle_lo = periodic periodic periodic
boundary.particle_hi = periodic periodic periodic

################
### NUMERICS ###
################
warpx.cfl = cfl
algo.maxwell_solver = yee
algo.particle_shape = 3
algo.particle_pusher = boris
warpx.use_filter = 1

#################
### PARTICLES ###
#################
particles.species_names = ele1 ele2

ele1.species_type = electron
ele1.injection_style = NRandomPerCell
ele1.num_particles_per_cell = 200
ele1.profile = constant
ele1.density = n0
ele1.momentum_distribution_type = maxwell_boltzmann
ele1.theta_distribution_type = constant
ele1.theta = T0 / (m_e * clight**2)
ele1.beta_distribution_type = parser
ele1.beta_function(x,y,z) = beta0
ele1.bulk_vel_dir = +z

ele2.species_type = electron
ele2.injection_style = NRandomPerCell
ele2.num_particles_per_cell = 200
ele2.profile = constant
ele2.density = n0
ele2.momentum_distribution_type = maxwell_boltzmann
ele2.theta_distribution_type = constant
ele2.theta = T0 / (m_e * clight**2)
ele2.beta_distribution_type = constant
ele2.beta = beta0
ele2.bulk_vel_dir = -z

###################
### DIAGNOSTICS ###
###################
# FULL
diagnostics.diags_names = particles
particles.intervals = floor(nt/200)
particles.diag_type = Full
particles.species = ele1 ele2
particles.fields_to_plot = none
particles.format = openpmd
particles.openpmd_backend = bp
particles.dump_last_timestep = 1
particles.ele1.variables = w z uz
particles.ele2.variables = w z uz

# REDUCED
warpx.reduced_diags_names = FieldEnergy FieldMaximum
FieldEnergy.type = FieldEnergy
FieldEnergy.intervals = 1
FieldMaximum.type = FieldMaximum
FieldMaximum.intervals = 1