#
# ExB_Filter_Exercise_1.py
#
# This file is used to calculate
# the Cartesian components of the acceleration of
# a charged particle through
# an E x B velocity filter.
#
# Here, it is assumed that the axis of the filter
# is aligned with the z-axis, that the magnetic field
# is along the +x-direction, and that the electric field
# is along the -y-direction.
#
# By:
# Ernest R. Behringer
# Department of Physics and Astronomy
# Eastern Michigan University
# Ypsilanti, MI 48197
# (734) 487-8799 (Office)
# ebehringe@emich.edu
#
# Last updated:
#
# 20110309 = March 9, 2011 ERB Initial writing in Matlab.
# 20160616 ERB conversion from Matlab.
#
from numpy import sqrt
import time
#
# Initialize parameter values
#
q = 1.60e-19 # particle charge [C]
m = 7.0*1.67e-27 # particle mass [kg]
KE_eV = 100.0 # particle kinetic energy [eV]
Ex = 0.0 # Ex = electric field in the +x direction [N/C]
Ey = -105.0 # Ey = electric field in the +y direction [N/C]
Ez = 0.0 # Ez = electric field in the +z direction [N/C]
Bx = 0.002 # Bx = magnetic field in the +x direction [T]
By = 0.0 # By = magnetic field in the +x direction [T]
Bz = 0.0 # Bz = magnetic field in the +x direction [T]
D = 2.0 # D = diameter of the exit aperture [mm]
L = 0.25 # L = length of the crossed field region [mm]
u = [1.0,1.0,100.0]/sqrt(10002.0) # direction of the velocity vector
# Derived quantities
qoverm = q/m # charge to mass ratio [C/kg]
KE = KE_eV*1.602e-19 # particle kinetic energy [J]
vmag = sqrt(2.0*KE/m) # particle velocity magnitude [m/s]
v1x = vmag*u[0] # v1x = x-component of the initial velocity [m/s]
v1y = vmag*u[1] # v1y = y-component of the initial velocity [m/s]
v1z = vmag*u[2] # v1z = z-component of the initial velocity [m/s]
#
# Calculate the Cartesian components of the acceleration
#
a_x = qoverm*(Ex + v1y*Bz - v1z*By)
a_y = qoverm*(Ey + v1z*Bx - v1x*Bz)
a_z = qoverm*(Ez + v1x*By - v1y*Bx)
print ("The magnitude of the initial velocity is %.3e"%vmag," m/s.") ##Frem:Added brackets
print ("The x-component of the acceleration is %.3e"%a_x," m/s$^2$.") #Frem:Added brackets
print ("The y-component of the acceleration is %.3e"%a_y," m/s$^2$.") #Frem:Added brackets
print ("The z-component of the acceleration is %.3e"%a_z," m/s$^2$.") #Frem:Added brackets
time.sleep(10)##Frem:Added Time to prevent the program from closing too fast