def __init__(self, pos=None, vel=None, t0=0, mass=None, charge=None, field=None):
"""
Object constructor.
Parameters
----------
pos: list or array
The initial position (x,y,z) of the particle, in meters.
vel: list or array
The initial velocity (vx, vy, vz) of the particle, in m/s.
t0: float
The time of simulation at the beginning (seconds), ignored for fields that do not depend on time.
mass: float
The mass of the particle, in kg.
charge: float
The charge of the particle, in Coulombs.
field: Field object
The field object that provides electric and magnetic field vectors and related quantities.
"""
self.pos = np.array(pos) # initial position array
self.vel = np.array(vel) # initial velocity array
self.tcur = t0 # current time
self.mass = mass # mass of the particle
self.charge = charge # charge of the particle
self.field = field # the field object
self.p = Particle(pos,vel,t0,mass,charge,field) # Store for referencing in setpa and setKE
self.p.check_adiabaticity = True
if self.p.isadiabatic():
g = GuidingCenter()
g.check_adiabaticity = True
g.init(self.p)
self.trajlist = [g]
else:
self.trajlist = [self.p]
def setke(self, ke, unit="ev"):
"""
Scale the velocity vector with the speed corresponding to the given kinetic energy.
Reinitializes the object.
Parameters
-----------
ke : float
The kinetic energy of the particle (eV by default). Can be relativistic.
unit : str, optional
The unit of the energy. If "ev", electron volts, otherwise Joule.
"""
self.p.setke(ke, unit)
self.p.check_adiabaticity = True
if self.p.isadiabatic():
g = GuidingCenter()
g.init(self.p)
g.check_adiabaticity = True
self.trajlist = [g]
else:
self.trajlist = [self.p]
def setpa(self, pa):
"""
Reinitialize the object with the given pitch angle (in degrees).
Modifies the velocity vector while keeping the energy constant so that
the particle's pitch angle (angle between the velocity and magnetic field
vectors) is `pa` degrees. Previous data is lost.
Parameters
-----------
pa : float
The new pitch angle in degrees.
"""
self.p.setpa(pa)
self.p.check_adiabaticity = True
if self.p.isadiabatic():
g = GuidingCenter()
g.init(self.p)
g.check_adiabaticity = True
self.trajlist = [g]
else:
self.trajlist = [self.p]
def advance(self,delta):
"""
Advance the tracer position and the relevant momentum for a given duration.
The trajectory is initialized at the latest state of the current tracer
and integrated for an additional `delta` seconds. Uses the settings
specific to the current tracer.
This method can be called many times.
Parameters
----------
delta : float
The number of seconds to advance the trajectory.
"""
t = 0
current = self.trajlist[-1]
assert current.check_adiabaticity == True
while t < delta:
try:
current.advance(delta-t)
except NonAdiabatic:
p = Particle()
p.init(current)
p.check_adiabaticity = True
self.trajlist.append(p)
current = self.trajlist[-1]
print("Switched to particle mode at time", current.tcur,flush=True)
except Adiabatic:
g = GuidingCenter()
g.init(current)
g.check_adiabaticity = True
self.trajlist.append(g)
current = self.trajlist[-1]
print("Switched to guiding center mode at time", current.tcur,flush=True)
t = current.tcur