def test_three_species(self):
"""
Test with three species (2 ions): D plasma with 5%H minority fraction
"""
n_3 = np.array([1, 1, 5 / 100]) * 1e19 / u.m**3
S, D, P = cold_plasma_permittivity_SDP(B, three_species, n_3, omega)
assert np.isclose(S, -11753.3)
assert np.isclose(D, 13408.99181054283)
assert np.isclose(P, -10524167.9)
def test_numpy_array_workflow(self):
"""
As per @jhillairet at:
https://github.com/PlasmaPy/PlasmaPy/issues/539#issuecomment-425337810
"""
ns = np.logspace(17, 19, 50) / u.m ** 3
B0 = 4 * u.T
omega_RF = 2 * np.pi * 50e6 * (u.rad / u.s)
S, D, P = cold_plasma_permittivity_SDP(
B=B0, species=["e", "D+"], n=[ns, ns], omega=omega_RF
)
assert S.shape == D.shape == P.shape == (50,)
def test_SD_to_LR_relationships(self):
"""
Test the relationships between (S, D, P) notation in Stix basis and
(L, R, P) notation in the rotating basis, ie test:
S = (R+L)/2 and D = (R-L)/2
and
R = S+D and L = S-D
"""
# test with a single species
S, D, _ = cold_plasma_permittivity_SDP(B, single_species, n, omega)
L, R, _ = cold_plasma_permittivity_LRP(B, single_species, n, omega)
assert np.isclose(R, S + D)
assert np.isclose(L, S - D)
assert np.isclose(S, (R + L) / 2)
assert np.isclose(D, (R - L) / 2)
def test_proton_electron_plasma(self):
"""
Test proton-electron plasma against the (approximate)
analytical formulas
"""
B = 1 * u.T
n = [1, 1] * 1 / u.m ** 3
omega = 1 * u.rad / u.s
omega_ce = gyrofrequency(B, particle="e", signed=True)
omega_pe = plasma_frequency(n[0], particle="e")
omega_cp = abs(omega_ce) / 1860
omega_pp = omega_pe / 43
S_analytical = (
1
- omega_pe ** 2 / (omega ** 2 - omega_ce ** 2)
- omega_pp ** 2 / (omega ** 2 - omega_cp ** 2)
)
D_analytical = +omega_ce / omega * omega_pe ** 2 / (
omega ** 2 - omega_ce ** 2
) + omega_cp / omega * omega_pp ** 2 / (omega ** 2 - omega_cp ** 2)
P_analytical = 1 - (omega_pe ** 2 + omega_pp ** 2) / omega ** 2
species = ["e", "p"]
S, D, P = tuple_result = cold_plasma_permittivity_SDP(B, species, n, omega)
assert tuple_result.sum is S
assert tuple_result.difference is D
assert tuple_result.plasma is P
assert isinstance(tuple_result, StixTensorElements)
assert np.isclose(S, S_analytical)
assert np.isclose(D, D_analytical)
assert np.isclose(P, P_analytical)
L, R, P = rotating_tuple_result = cold_plasma_permittivity_LRP(
B, species, n, omega
)
assert rotating_tuple_result.left is L
assert rotating_tuple_result.right is R
assert rotating_tuple_result.plasma is P
assert isinstance(rotating_tuple_result, RotatingTensorElements)
