calculate_LStar

rbinvariantslib.invariants.calculate_LStar(model: MagneticFieldModel, starting_point, mode='normal', starting_mirror_latitude=None, Bm=None, starting_pitch_angle=None, integrand_atol=0.01, integrand_rtol=0.01, num_local_times=16, first_mlt_step=0.39269908169872414, max_mlt_step=1.5707963267948966, major_step=0.05, minor_step=0.01, interval_size_threshold=0.05, rel_error_threshold=0.01, max_iters=300, trace_step_size=None, interp_local_times=True, interp_npoints=1024, verbose=False) → CalculateLStarResult

Calculate the third adiabatic invariant, L*

Can be run in two modes, ‘normal and ‘equitorial’. The normal mode searches for a drift shell by selecting a field line that matches K at each local time; the equitorial mode matches Bmin at each local time.

Parameters:

modelMagneticFieldModel

grid and magnetic field, loaded using models module

starting_pointtuple of floats

Starting point of the field line integration, as (x, y, z) tuple of floats, in units of Re

mode{‘normal’, ‘equitorial’}, optional

Mode to run drift shell search in. Equitorial mode does special search using Bmin, which is faster. Overrides starting_mirror_latitude, Bm, and starting_pitch_angle.

starting_mirror_latitudefloat, optional

Latitude in degrees to use for the mirroring point for the local time associated with the starting point to calculate drift shell

Bmfloat, optional

Magnetic field strength at mirror point used to calculate drift shell

starting_pitch_anglefloat, optional

Pitch angle at Bmin at starting point to calcualte the drift shell. If set to 90.0, then a special path will be taken through the code where the drift shell is used by searching for isolines of Bmin instead of K

major_stepfloat, optional

Size of large step (float, units of Re) to find rough location of drift shell radius

num_local_times‘adaptive’ or int

Number of local times to use. If ‘adaptive’ is passed, uses a Runge-Kutta method.

minor_stepfloat, optional

Size of small step (float, units of Re) to refine drift shell radius

interval_size_thresholdfloat, optional

Only used by mode=’bisection’. Bisection threshold before linearly interpolating

max_itersint, optional

Used by all modes. Maximum iterations before raising exception.

trace_step_sizefloat, optional

Used by all modes. step size used to trace field lines

interp_local_timesbool, optional

Interpolate intersection latitudes for local times with cubic splines to allow for less local time calculation

interp_npointsint, optional

Number of points to usein interplation, only active if interp_local_times=True

Returns:

result: CalculateLStarResult