Add structure for proton-boron fusion module (#2217)

* Add structure for proton-boron fusion module

* Fix clang compile error

* Generalize structure for other nuclear fusion types

* Workaround: try to use std::vectors to fix clang compile error

* Simplify workaround for clang

* Rebase on 2245 and add empty particle creation functor

* Apply suggestions from code review

Co-authored-by: Axel Huebl <axel.huebl@plasma.ninja>

* Add couple of consts and runtime assert

* Add another const

Co-authored-by: Axel Huebl <axel.huebl@plasma.ninja>

1 files changed, 45 insertions, 0 deletions

diff --git a/Source/Particles/Collision/BinaryCollision/ParticleCreationFunc.cpp b/Source/Particles/Collision/BinaryCollision/ParticleCreationFunc.cpp
new file mode 100644
index 000000000..fff4150c1
--- /dev/null
+++ b/Source/Particles/Collision/BinaryCollision/ParticleCreationFunc.cpp
@@ -0,0 +1,45 @@
+/* Copyright 2021 Neil Zaim
+ *
+ * This file is part of WarpX.
+ *
+ * License: BSD-3-Clause-LBNL
+ */
+
+#include "ParticleCreationFunc.H"
+
+#include "BinaryCollisionUtils.H"
+#include "Particles/MultiParticleContainer.H"
+
+#include <AMReX_GpuContainers.H>
+#include <AMReX_ParmParse.H>
+#include <AMReX_Vector.H>
+
+#include <string>
+
+ParticleCreationFunc::ParticleCreationFunc (const std::string collision_name,
+                                            MultiParticleContainer const * const mypc)
+    {
+        amrex::ParmParse pp_collision_name(collision_name);
+
+        m_collision_type = BinaryCollisionUtils::get_collision_type(collision_name, mypc);
+
+#ifdef AMREX_USE_GPU
+        amrex::Vector<int> host_num_products;
+#else
+        amrex::Gpu::DeviceVector<int>& host_num_products = m_num_products;
+#endif
+        if (m_collision_type == CollisionType::ProtonBoronFusion)
+            {
+                // Proton-Boron fusion only produces alpha particles
+                m_num_product_species = 1;
+                // Proton-Boron fusion produces 3 alpha particles per fusion reaction
+                host_num_products.push_back(3);
+            }
+#ifdef AMREX_USE_GPU
+        m_num_products.resize(m_num_product_species);
+        amrex::Gpu::copyAsync(amrex::Gpu::hostToDevice, host_num_products.begin(),
+                              host_num_products.end(),
+                              m_num_products.begin());
+        amrex::Gpu::streamSynchronize();
+#endif
+    }