Fix restart with ionization and add automated test (BLAST-WarpX#6291)

PR BLAST-WarpX#5481 replaced `NewIntComp` (which can be called several times with
the same real time component) with `AddIntComp` (which can only be
called only once on a real-time component, and raises an error if it is
called a second time).

As a consequence, simulations that involve field ionization now abort
during restart, with the following message:
```
 AddIntComp: name 'ionizationLevel' is already present in the SoA. SIGABRT
```
as reported in BLAST-WarpX#1546

This is because `AddIntComp` is first called for `ionizationLevel` here:

https://github.com/BLAST-WarpX/warpx/blob/development/Source/Diagnostics/ParticleIO.cpp#L219
and later added again here:

https://github.com/BLAST-WarpX/warpx/blob/development/Source/Particles/PhysicalParticleContainer.cpp#L1516

This PR avoids the second call by adding an `if` condition. It also adds
a restart test. (The test fails when using the `development` branch,
because the code aborts during restart.)

Author: RemiLehe

Examples/Tests/field_ionization/CMakeLists.txt

@@ -21,6 +21,17 @@ add_warpx_test(
     OFF  # dependency
 )
 
+
+add_warpx_test(
+    test_2d_ionization_lab_restart  # name
+    2  # dims
+    2  # nprocs
+    inputs_test_2d_ionization_lab_restart  # inputs
+    "analysis.py diags/diag1001600"  # analysis
+    "analysis_default_regression.py --path diags/diag1001600 --rtol 1e-2"  # checksum
+    test_2d_ionization_lab  # dependency
+)
+
 add_warpx_test(
     test_2d_ionization_picmi  # name
     2  # dims

Examples/Tests/field_ionization/inputs_test_2d_ionization_lab

@@ -52,6 +52,11 @@ laser1.profile_focal_distance = 0
 laser1.wavelength = 0.8e-6
 
 # Diagnostics
-diagnostics.diags_names = diag1
+diagnostics.diags_names = diag1 chk
+
 diag1.intervals = 10000
 diag1.diag_type = Full
+
+chk.intervals = 1000
+chk.diag_type = Full
+chk.format = checkpoint

Examples/Tests/field_ionization/inputs_test_2d_ionization_lab_restart

@@ -0,0 +1,5 @@
+# base input parameters
+FILE = inputs_test_2d_ionization_lab
+
+# test input parameters
+amr.restart = "../test_2d_ionization_lab/diags/chk001000"

Regression/Checksum/benchmarks_json/test_2d_ionization_lab.json

@@ -8,24 +8,24 @@
     "Ez": 3028.1738497993415,
     "jx": 1.2111358355443756e+16,
     "jy": 0.0,
-    "jz": 1.3638088639277835e-07
+    "jz": 1.3637783796991858e-07
   },
   "ions": {
     "particle_ionizationLevel": 72897.0,
     "particle_momentum_x": 1.7613240076033055e-18,
     "particle_momentum_y": 0.0,
-    "particle_momentum_z": 3.6186967472865243e-23,
+    "particle_momentum_z": 3.618696747286525e-23,
     "particle_position_x": 0.03200001180710321,
     "particle_position_y": 0.12800000462171646,
     "particle_weight": 9.999999999999999e-11
   },
   "electrons": {
-    "particle_momentum_x": 4.433634396795001e-18,
+    "particle_momentum_x": 4.433468593927309e-18,
     "particle_momentum_y": 0.0,
-    "particle_momentum_z": 2.6671140603432366e-18,
-    "particle_orig_z": 0.4301725637223404,
-    "particle_position_x": 0.11022808158588382,
-    "particle_position_y": 0.6413954792104292,
+    "particle_momentum_z": 2.6671137299190897e-18,
+    "particle_orig_z": 0.4301725637223405,
+    "particle_position_x": 0.11022808329781983,
+    "particle_position_y": 0.6413952835649748,
     "particle_weight": 3.443203124999999e-10
   }
 }

Source/Particles/PhysicalParticleContainer.cpp

@@ -1513,7 +1513,9 @@ PhysicalParticleContainer::InitIonizationModule ()
         physical_element == "H" || !do_adk_correction,
         "Correction to ADK by Zhang et al., PRA 90, 043410 (2014) only works with Hydrogen");
     // Add runtime integer component for ionization level
-    AddIntComp("ionizationLevel");
+    if (!HasiAttrib("ionizationLevel")) {
+        AddIntComp("ionizationLevel");
+    }
     // Get atomic number and ionization energies from file
     const int ion_element_id = utils::physics::ion_map_ids.at(physical_element);
     ion_atomic_number = utils::physics::ion_atomic_numbers[ion_element_id];