ZFEL SASE¶

Basic example of a SASE simulation.

In [1]:

# (optional) installation
# !pip install git+https://github.com/slaclab/zfel.git@devel

# (optional) installation # !pip install git+https://github.com/slaclab/zfel.git@devel

In [2]:

from zfel import sase1d
import zfel.plot

import numpy as np

import matplotlib.pyplot as plt
%matplotlib inline
%config InlineBackend.figure_format = 'retina'

from zfel import sase1d import zfel.plot import numpy as np import matplotlib.pyplot as plt %matplotlib inline %config InlineBackend.figure_format = 'retina'

Input¶

In [3]:

sase_input = dict(
    npart   = 512,                       # n-macro-particles per bucket 
    s_steps = 200,                      # n-sample points along bunch length
    z_steps = 200,                      # n-sample points along undulator
    energy  = 4313.34e6,                # electron energy [eV]
    eSpread = 0,                       # relative rms energy spread [1]
    emitN   = 1.2e-6,                    # normalized transverse emittance [m-rad]
    currentMax = 3400,                   # peak current [Ampere]
    beta = 26,                          # mean beta [meter]
    unduPeriod = 0.03,                 # undulator period [meter]
    unduK = 3.5 ,          # undulator parameter, K [1], array could taper. 
    unduL = 70,                         # length of undulator [meter]
    radWavelength=None,                 # Will calculate based on resonance condition for unduK[0]
    random_seed=31,                     # for reproducibility
    particle_position=None, #np.genfromtxt('./Inputs/particle_position.csv', delimiter=',') # or None,
    hist_rule='square-root',             # 'square-root' or 'sturges' or 'rice-rule' or 'self-design', number \
                                       #  of intervals to generate the histogram of eta value in a bucket
    iopt='sase',
    P0 = 0                            # small seed input power [W]
)

sase_input = dict( npart = 512, # n-macro-particles per bucket s_steps = 200, # n-sample points along bunch length z_steps = 200, # n-sample points along undulator energy = 4313.34e6, # electron energy [eV] eSpread = 0, # relative rms energy spread [1] emitN = 1.2e-6, # normalized transverse emittance [m-rad] currentMax = 3400, # peak current [Ampere] beta = 26, # mean beta [meter] unduPeriod = 0.03, # undulator period [meter] unduK = 3.5 , # undulator parameter, K [1], array could taper. unduL = 70, # length of undulator [meter] radWavelength=None, # Will calculate based on resonance condition for unduK[0] random_seed=31, # for reproducibility particle_position=None, #np.genfromtxt('./Inputs/particle_position.csv', delimiter=',') # or None, hist_rule='square-root', # 'square-root' or 'sturges' or 'rice-rule' or 'self-design', number \ # of intervals to generate the histogram of eta value in a bucket iopt='sase', P0 = 0 # small seed input power [W] )

Intermediate parameters¶

These are used internally

In [4]:

params = sase1d.params_calc(**sase_input)
params.keys()

params = sase1d.params_calc(**sase_input) params.keys()

Out[4]:

dict_keys(['unduJJ', 'gamma0', 'sigmaX2', 'kappa_1', 'density', 'Kai', 'ku', 'resWavelength', 'Pbeam', 'coopLength', 'z0', 'delt', 'dels', 'E02', 'gbar', 'delg', 'Ns', 'deta', 'rho'])

Run¶

In [5]:

%%time
output = sase1d.sase(sase_input)

%%time output = sase1d.sase(sase_input)

CPU times: user 7.52 s, sys: 1.31 ms, total: 7.52 s
Wall time: 7.52 s

In [6]:

output.keys()

output.keys()

Out[6]:

dict_keys(['Er', 'Ei', 'thet_final', 'eta_final', 'theta_final_slice_history', 'eta_final_slice_history', 'power_s', 'power_z', 'spectrum', 'params', 's', 'z', 'bunchLength', 'bunch_steps', 'freq'])

Plot output¶

In [7]:

plt.ylabel('Power (GW)')
plt.xlabel('z (m)')
plt.plot(output['z'], output['power_z']/1e9)

plt.ylabel('Power (GW)') plt.xlabel('z (m)') plt.plot(output['z'], output['power_z']/1e9)

Out[7]:

[<matplotlib.lines.Line2D at 0x7ff28fe31280>]

In [8]:

# Power evolution. z vs slice
plt.imshow( (output['Er']**2 + output['Ei']**2).T, origin='lower')

# Power evolution. z vs slice plt.imshow( (output['Er']**2 + output['Ei']**2).T, origin='lower')

Out[8]:

<matplotlib.image.AxesImage at 0x7ff2870c1670>

In [9]:

zfel.plot.plot_log_power_z(output)

zfel.plot.plot_log_power_z(output)

In [10]:

zfel.plot.plot_power_s(output)

zfel.plot.plot_power_s(output)

In [11]:

# plot spectrum
freq = output['freq']
spectrum = output['spectrum']
plt.plot(freq,spectrum[1:,-1])
plt.xlabel('energy (eV)')
plt.ylabel('spectrum (W/?)')

# plot spectrum freq = output['freq'] spectrum = output['spectrum'] plt.plot(freq,spectrum[1:,-1]) plt.xlabel('energy (eV)') plt.ylabel('spectrum (W/?)')

Out[11]:

Text(0, 0.5, 'spectrum (W/?)')

Particle history of final slice¶

In [12]:

theta = output['theta_final_slice_history']
eta = output['eta_final_slice_history']
_, n_step = theta.shape

# particles, step along z
theta.shape

theta = output['theta_final_slice_history'] eta = output['eta_final_slice_history'] _, n_step = theta.shape # particles, step along z theta.shape

Out[12]:

(512, 201)

In [13]:

# Function to plot a single step
def plot_step(i):
    
    x = (theta[:,i] % 2*np.pi)/(2*np.pi) * 360
    y = eta[:,i]*1e3
    
    fig, ax = plt.subplots()
    
    ax.set_title(f'Final slice, Step {i}')
    ax.set_ylim(-6,6)
    ax.set_xlabel(r'$\theta\, (deg)$')
    ax.set_ylabel(r'$ \eta\, (10^{-3})$')
    ax.scatter(x, y, marker='.', color='black')

plot_step(n_step-1)

# Function to plot a single step def plot_step(i): x = (theta[:,i] % 2*np.pi)/(2*np.pi) * 360 y = eta[:,i]*1e3 fig, ax = plt.subplots() ax.set_title(f'Final slice, Step {i}') ax.set_ylim(-6,6) ax.set_xlabel(r'$\theta\, (deg)$') ax.set_ylabel(r'$ \eta\, (10^{-3})$') ax.scatter(x, y, marker='.', color='black') plot_step(n_step-1)

In [14]:

# interactive
#from ipywidgets import interact
#import ipywidgets as widgets

#interact(plot_step, i=widgets.IntSlider(min=0, max=n_step-1, step=1, value=n_step//2));

# interactive #from ipywidgets import interact #import ipywidgets as widgets #interact(plot_step, i=widgets.IntSlider(min=0, max=n_step-1, step=1, value=n_step//2));