Include `J` in diagnostic output when an electromagnetic solver is not used (#4116)

* include current density in diagnostic output even if an electromagnetic solver is not used

* do not redeposit current for the magnetostatic solver

* update CI benchmarks for tests that previously did not register current density

* fix remaining failing CI test

* Apply suggestions from code review

Co-authored-by: Edoardo Zoni <59625522+EZoni@users.noreply.github.com>

* do not output current density in collision tests

* update `JFunctor` constructor doc-string

* code cleanup - reduce code duplication

* specify `Ex Ey Ez Bx By Bz` fields to plot for collision CI tests

* specify `Er Et Ez Br Bt Bz` as output for rz collision test

* rename `InterpolateToDst` to `InterpolateMFForDiag`

* only deposit current density once per diagnostic output (if not already deposited)

* write deposited current for all directions into `current_fp` during diagnostic step deposition

* use `amrex::make_alias` to directly deposit current density into `warpx.current_fp` during diagnostic step deposition

* add class variable `solver_deposits_current` to `FullDiagnostics` so that there is only one place where the determination is made whether current should be deposited during diagnostic output

* correct logic to determine `m_solver_deposits_current`

---------

Co-authored-by: Edoardo Zoni <59625522+EZoni@users.noreply.github.com>

1 files changed, 59 insertions, 0 deletions

diff --git a/Source/Diagnostics/ComputeDiagFunctors/JFunctor.cpp b/Source/Diagnostics/ComputeDiagFunctors/JFunctor.cpp
new file mode 100644
index 000000000..4663a5e1a
--- /dev/null
+++ b/Source/Diagnostics/ComputeDiagFunctors/JFunctor.cpp
@@ -0,0 +1,59 @@
+/* This file is part of WarpX.
+ *
+ * Authors: Roelof Groenewald
+ * License: BSD-3-Clause-LBNL
+ */
+
+#include "JFunctor.H"
+
+#include "Particles/MultiParticleContainer.H"
+#include "WarpX.H"
+
+#include <AMReX.H>
+#include <AMReX_IntVect.H>
+#include <AMReX_MultiFab.H>
+
+JFunctor::JFunctor (const int dir, int lev,
+                   amrex::IntVect crse_ratio,
+                   bool convertRZmodes2cartesian,
+                   bool deposit_current, int ncomp)
+    : ComputeDiagFunctor(ncomp, crse_ratio), m_dir(dir), m_lev(lev),
+      m_convertRZmodes2cartesian(convertRZmodes2cartesian),
+      m_deposit_current(deposit_current)
+{ }
+
+void
+JFunctor::operator() (amrex::MultiFab& mf_dst, int dcomp, const int /*i_buffer*/) const
+{
+    auto& warpx = WarpX::GetInstance();
+    /** pointer to source multifab (can be multi-component) */
+    amrex::MultiFab* m_mf_src = warpx.get_pointer_current_fp(m_lev, m_dir);
+
+    // Deposit current if no solver or the electrostatic solver is being used
+    if (m_deposit_current)
+    {
+        // allocate temporary multifab to deposit current density into
+        amrex::Vector<std::array< std::unique_ptr<amrex::MultiFab>, 3 > > current_fp_temp;
+        current_fp_temp.resize(1);
+
+        auto& current_fp_x = warpx.getcurrent_fp(m_lev,0);
+        current_fp_temp[0][0] = std::make_unique<amrex::MultiFab>(
+            current_fp_x, amrex::make_alias, 0, current_fp_x.nComp()
+        );
+
+        auto& current_fp_y = warpx.getcurrent_fp(m_lev,1);
+        current_fp_temp[0][1] = std::make_unique<amrex::MultiFab>(
+            current_fp_y, amrex::make_alias, 0, current_fp_y.nComp()
+        );
+        auto& current_fp_z = warpx.getcurrent_fp(m_lev,2);
+        current_fp_temp[0][2] = std::make_unique<amrex::MultiFab>(
+            current_fp_z, amrex::make_alias, 0, current_fp_z.nComp()
+        );
+
+        auto& mypc = warpx.GetPartContainer();
+        mypc.DepositCurrent(current_fp_temp, warpx.getdt(m_lev), 0.0);
+    }
+
+    InterpolateMFForDiag(mf_dst, *m_mf_src, dcomp, warpx.DistributionMap(m_lev),
+                         m_convertRZmodes2cartesian);
+}