Python: Deposit Charge (#612)

Add a Python function `ImpactX.deposit_charge()` that deposits the
current particle beam into x,y,z `rho`, independent of space charge
logic and not applying any kicks to the beam.

Useful for debugging and experimenting with new algorithms.

src/python/ImpactX.cpp

@@ -6,6 +6,7 @@
 #include "pyImpactX.H"
 
 #include <ImpactX.H>
+#include <particles/transformation/CoordinateTransformation.H>
 
 #include <AMReX.H>
 #include <AMReX_ParmParse.H>
@@ -360,6 +361,32 @@ void init_ImpactX (py::module& m)
             "``0`` for silent, higher is more verbose. Default is ``1``."
         )
 
+        .def("deposit_charge",
+            [](ImpactX & ix) {
+                // transform from x',y',t to x,y,z
+                transformation::CoordinateTransformation(
+                        *(ix.amr_data)->m_particle_container,
+                        CoordSystem::t);
+
+                // Note: The following operation assume that
+                // the particles are in x, y, z coordinates.
+
+                // Resize the mesh, based on `m_particle_container` extent
+                ix.ResizeMesh();
+
+                // Redistribute particles in the new mesh in x, y, z
+                ix.amr_data->m_particle_container->Redistribute();
+
+                // charge deposition
+                ix.amr_data->m_particle_container->DepositCharge(ix.amr_data->m_rho, ix.amr_data->refRatio());
+
+                // transform from x,y,z to x',y',t
+                transformation::CoordinateTransformation(*(ix.amr_data)->m_particle_container,
+                                                         CoordSystem::s);
+            },
+            "Deposit charge in x,y,z."
+        )
+
         .def("finalize", &ImpactX::finalize,
              "Deallocate all contexts and data."
         )

tests/python/test_charge_deposition.py

@@ -25,7 +25,6 @@ def test_charge_deposition(save_png=True):
 
     sim.n_cell = [16, 24, 32]
     sim.load_inputs_file(basepath + "/examples/fodo/input_fodo.in")
-    sim.space_charge = True
     sim.slice_step_diagnostics = False
 
     # Future:
@@ -41,6 +40,8 @@ def test_charge_deposition(save_png=True):
 
     sim.evolve()
 
+    sim.deposit_charge()
+
     rho = sim.rho(lev=0)
     rs = rho.sum_unique(comp=0, local=False)