Add space-charge to Cheetah

CHANGELOG.md

@@ -11,6 +11,7 @@
 - `CustomTransferMap` elements created by combining multiple other elements will now reflect that in their `name` attribute (see #100) (@jank324)
 - Add a new class method for `ParticleBeam` to generate a 3D uniformly distributed ellipsoidal beam (see #146) (@cr-xu, @jank324)
 - Add Python 3.12 support (see #161) (@jank324)
+- Implement space charge using Green's function in a `SpaceChargeKick` element (see #142) (@greglenerd, @RemiLehe, @ax3l, @cr-xu, @jank324)
 
 ### 🐛 Bug fixes
 

cheetah/__init__.py

@@ -13,6 +13,7 @@
     Screen,
     Segment,
     Solenoid,
+    SpaceChargeKick,
     Undulator,
     VerticalCorrector,
 )

cheetah/accelerator/__init__.py

@@ -12,5 +12,6 @@
 from .screen import Screen  # noqa: F401
 from .segment import Segment  # noqa: F401
 from .solenoid import Solenoid  # noqa: F401
+from .space_charge_kick import SpaceChargeKick  # noqa: F401
 from .undulator import Undulator  # noqa: F401
 from .vertical_corrector import VerticalCorrector  # noqa: F401

cheetah/accelerator/quadrupole.py

@@ -114,7 +114,7 @@ def plot(self, ax: plt.Axes, s: float) -> None:
     def defining_features(self) -> list[str]:
         return super().defining_features + ["length", "k1", "misalignment", "tilt"]
 
-    def __repr__(self) -> None:
+    def __repr__(self) -> str:
         return (
             f"{self.__class__.__name__}(length={repr(self.length)}, "
             + f"k1={repr(self.k1)}, "