Create Custom Charges

Custom charge trajectories can be simulated in PyCharge by creating custom subclasses of the Charge class and defining its motion along the \(x\), \(y\), and \(z\) directions as functions of time. Below is an example of a custom charge class called ExampleCharge which oscillates along the \(z\) axis with a charge \(q\), angular frequency, and amplitude set during instantiation:

from scipy.constants import e
from numpy import cos

class ExampleCharge(Charge):

    def __init__(self, q=e, omega_0=1e12, amplitude=1e-9):
        super().__init__(q)
        self.omega_0 = omega_0
        self.amplitude = amplitude

    def xpos(self, t):
        return 0

    def ypos(self, t):
        return 0

    def zpos(self, t):
        return self.amplitude*cos(self.omega_0*t)

Since the equations defining the velocity and acceleration are not defined, they are calculated by PyCharge using discrete derivative approximations. Objects instantiated from the ExampleCharge class can now be used as sources in PyCharge simulations.