"""Define the rf field corresponding to ``FIELD_MAP 100``.
This is 1D longitudinal field along ``z``. The only one that is completely
implemented for now.
"""
import functools
import math
from collections.abc import Callable
from pathlib import Path
import numpy as np
from lightwin.core.em_fields.field import Field
from lightwin.core.em_fields.field_helpers import (
create_1d_field_func,
shifted_e_spat,
)
from lightwin.core.em_fields.types import Pos1D
from lightwin.tracewin_utils.electromagnetic_fields import (
is_a_valid_1d_electric_field,
rescale,
)
from lightwin.tracewin_utils.field_map_loaders import field_1d
[docs]
class Field100(Field):
"""Define a RF field, 1D longitudinal."""
extensions = (".edz",)
is_implemented = True
[docs]
def _load_fieldmap(
self, path: Path, **validity_check_kwargs
) -> tuple[Callable[[Pos1D], float], tuple[int], int]:
r"""Load a 1D field (``EDZ`` extension).
Parameters
----------
path : pathlib.Path
The path to the ``EDZ`` file to load.
Returns
-------
e_z : Callable[[Pos1D], float]
Function that takes in ``z`` position and returns corresponding
field, at null phase, for amplitude of :math:`1\,\mathrm{MV/m}`.
n_z : tuple[int]
Number of interpolation points.
n_cell : int
Number of cell for cavities.
"""
n_z, zmax, norm, f_z, n_cell = field_1d(path)
assert is_a_valid_1d_electric_field(
n_z, zmax, f_z, self._length_m
), f"Error loading {path}'s field map."
f_z = rescale(f_z, norm)
z_positions = np.linspace(0.0, zmax, n_z + 1)
e_z = create_1d_field_func(f_z, z_positions)
return e_z, (n_z,), n_cell
[docs]
def shift(self) -> None:
"""Shift the electric field map.
.. warning::
You must ensure that for ``z < 0`` and ``z > element.length_m`` the
electric field is null. Interpolation can lead to funny results!
"""
assert hasattr(
self, "z_0"
), "You need to set the starting_position attribute of the Field."
shifted = functools.partial(
shifted_e_spat, e_spat=self._e_z_spat_rf, z_shift=self.z_0
)
self._e_z_spat_rf = shifted
[docs]
def e_z(
self, pos: Pos1D, phi: float, amplitude: float, phi_0_rel: float
) -> complex:
"""Give longitudinal electric field value."""
return (
amplitude
* self._e_z_spat_rf(pos)
* (math.cos(phi + phi_0_rel) + 1j * math.sin(phi + phi_0_rel))
)