Different species for secondary electrons

The option to have a different species than the impacting electron for
secondary electrons from ionization is introduced.

src/modules/init/moduleInput.f90

@@ -634,7 +634,7 @@ MODULE moduleInput
       INTEGER:: i, k, ij
       INTEGER:: pt_i, pt_j
       REAL(8):: energyThreshold, energyBinding
-      CHARACTER(:), ALLOCATABLE:: electron
+      CHARACTER(:), ALLOCATABLE:: electron, electronSecondary
       INTEGER:: e
       CLASS(meshCell), POINTER:: cell
 
@@ -711,8 +711,16 @@ MODULE moduleInput
                 IF (.NOT. found) CALL criticalError('energyThreshold not found for collision' // object, 'readInteractions')
                 CALL config%get(object // '.electron', electron, found)
                 IF (.NOT. found) CALL criticalError('electron not found for collision' // object, 'readInteractions')
-                CALL initBinaryIonization(interactionMatrix(ij)%collisions(k)%obj, &
-                                          crossSecFilePath, energyThreshold, electron)
+                CALL config%get(object // '.electronSecondary', electronSecondary, found)
+                IF (found) THEN
+                  CALL initBinaryIonization(interactionMatrix(ij)%collisions(k)%obj, &
+                                            crossSecFilePath, energyThreshold, electron, electronSecondary)
+
+                ELSE
+                  CALL initBinaryIonization(interactionMatrix(ij)%collisions(k)%obj, &
+                                            crossSecFilePath, energyThreshold, electron)
+
+                END IF
 
               CASE ('recombination')
                 !Electorn impact ionization

src/modules/moduleCollisions.f90

@@ -43,7 +43,8 @@ MODULE moduleCollisions
   TYPE, EXTENDS(collisionBinary):: collisionBinaryIonization
     REAL(8):: eThreshold !Minimum energy (non-dimensional units) required for ionization
     REAL(8):: deltaV !Change in velocity due to exchange of eThreshold
-    CLASS(speciesCharged), POINTER:: electron !Pointer to species considerer as electrons
+    CLASS(speciesCharged), POINTER:: electron          !Pointer to species considerer as electrons
+    CLASS(speciesCharged), POINTER:: electronSecondary !Pointer to species considerer as secondary electron
     CONTAINS
       PROCEDURE, PASS:: collide => collideBinaryIonization
 
@@ -241,7 +242,7 @@ MODULE moduleCollisions
 
     !ELECTRON IMPACT IONIZATION
     !Inits electron impact ionization
-    SUBROUTINE initBinaryIonization(collision, crossSectionFilename, energyThreshold, electron)
+    SUBROUTINE initBinaryIonization(collision, crossSectionFilename, energyThreshold, electron, electronSecondary)
       USE moduleTable
       USE moduleRefParam
       USE moduleConstParam
@@ -253,7 +254,8 @@ MODULE moduleCollisions
       CHARACTER(:), ALLOCATABLE, INTENT(in):: crossSectionFilename
       REAL(8), INTENT(in):: energyThreshold
       CHARACTER(:), ALLOCATABLE, INTENT(in):: electron
-      INTEGER:: electronIndex
+      CHARACTER(:), ALLOCATABLE, OPTIONAL, INTENT(in):: electronSecondary
+      INTEGER:: electronIndex, electronSecondaryIndex
 
       ALLOCATE(collisionBinaryIonization:: collision)
 
@@ -278,10 +280,27 @@ MODULE moduleCollisions
 
         CLASS DEFAULT
           CALL criticalError("Species " // sp%name // " chosen for " // &
-                             "secondary electron is not a charged species", 'initBinaryIonization')
+                             "impacting electron is not a charged species", 'initBinaryIonization')
 
         END SELECT
 
+        IF (PRESENT(electronSecondary)) THEN
+          electronSecondaryIndex = speciesName2Index(electronSecondary)
+          SELECT TYPE(sp => species(electronSecondaryIndex)%obj)
+          TYPE IS(speciesCharged)
+            collision%electronSecondary => sp
+
+          CLASS DEFAULT
+            CALL criticalError("Species " // sp%name // " chosen for " // &
+                               "secondary electron is not a charged species", 'initBinaryIonization')
+
+          END SELECT
+
+        ELSE
+          collision%electronSecondary => NULL()
+
+        END IF
+
         !momentum change per ionization process
         collision%deltaV = sqrt(collision%eThreshold / collision%electron%m)
 
@@ -336,6 +355,12 @@ MODULE moduleCollisions
         !Copy basic information from primary electron
         newElectron = electron
 
+        !If secondary electron species indicates, convert
+        IF (ASSOCIATED(self%electronSecondary)) THEN
+          newElectron%species => self%electronSecondary
+
+        END IF
+
         !Secondary electorn gains energy from ionization
         newElectron%v       =  vChange