Interactive finite-length current profile

In this example the current per unit length is plotted along a cylindrical probe, allowing the user to interactively change then length and voltage of the probe. All quantities are normalized.

import matplotlib
import matplotlib.pyplot as plt
from matplotlib.widgets import Slider
from langmuir import *
from scipy.special import erf

normalization='OML'

elec = Electron()
geo = Cylinder(r=0.1*elec.debye, l=20*elec.debye)
z = np.linspace(0, 20, 1000)
I = finite_length_current_density(geo, elec, zeta=z, eta=25, normalization=normalization)

len_min = 1
len_max = 40
eta_min = -10
eta_max = 100

fig, ax = plt.subplots()
plt.subplots_adjust(bottom=0.25)
line, = plt.plot(z, I)
if normalization=='th':
    ax.axis([-5, len_max+5, 0.5, 20])
else:
    ax.axis([-5, len_max+5, 0.5, 4.5])
ax.grid()
plt.xlabel(r'$z/\lambda_D$')
plt.ylabel(r'$I/I_\mathrm{OML}$')

ax_len = plt.axes([0.1, 0.10, 0.8, 0.03])
ax_eta = plt.axes([0.1, 0.05, 0.8, 0.03])
sl_len = Slider(ax_len, r'$l/\lambda_D$', 1, len_max, valinit=20)
sl_eta = Slider(ax_eta, r'$\eta$', eta_min, eta_max, valinit=25)

def update(val):
    eta = sl_eta.val
    l = sl_len.val
    z = np.linspace(0, l, 1000)
    geo = Cylinder(r=0.1*elec.debye, l=l*elec.debye)
    I = finite_length_current_density(geo, elec, zeta=z, eta=eta, normalization=normalization)
    line.set_ydata(I)
    line.set_xdata(z)

sl_len.on_changed(update)
sl_eta.on_changed(update)

plt.show()