[mini] Add radius to fixed weight beams (#1006)

* add option to add a radius * typo * set default radius to inf * move propagation after cut and fix doc * make ballistic propagation depend on single particle momentum
Hi-PACE · Aug 9, 2023 · b587430 · b587430
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Showing 4 changed files with 17 additions and 13 deletions.
diff --git a/docs/source/run/parameters.rst b/docs/source/run/parameters.rst
@@ -426,6 +426,10 @@ which are valid only for certain beam types, are introduced further below under
 * ``<beam name>.zmax`` (`float`) (default `infinity`)
     Maximum in `z` at which particles are injected.
 
+* ``<beam name>.radius`` (`float`)
+    Maximum radius ``<beam name>.radius`` :math:`= \sqrt{x^2 + y^2}` within that particles are
+    injected.
+
 * ``<beam name>.element`` (`string`) optional (default `electron`)
     The Physical Element of the plasma. Sets charge, mass and, if available,
     the specific Ionization Energy of each state.
@@ -520,10 +524,6 @@ Option: ``fixed_ppc``
 * ``<beam name>.ppc`` (3 `int`) (default `1 1 1`)
     Number of particles per cell in `x`-, `y`-, and `z`-direction to generate the beam.
 
-* ``<beam name>.radius`` (`float`)
-    Maximum radius ``<beam name>.radius`` :math:`= \sqrt{x^2 + y^2}` within that particles are
-    injected.
-
 * ``<beam name>.density`` (`float`)
     Peak density of the beam.
     The absolute value of this parameter is used when initializing the beam.

diff --git a/src/particles/beam/BeamParticleContainer.H b/src/particles/beam/BeamParticleContainer.H
@@ -96,7 +96,8 @@ public:
                               const amrex::Real total_charge,
                               const amrex::Real z_foc,
                               const bool do_symmetrize,
-                              const bool can, const amrex::Real zmin, const amrex::Real zmax);
+                              const bool can, const amrex::Real zmin, const amrex::Real zmax,
+                              const amrex::Real radius);
 
 #ifdef HIPACE_USE_OPENPMD
     /** Checks the input file first to determine its Datatype
@@ -218,7 +219,7 @@ private:
     amrex::IntVect m_ppc {1, 1, 1}; /**< Number of particles per cell in each direction */
     amrex::Real m_zmin; /**< Min longitudinal particle position of the beam */
     amrex::Real m_zmax; /**< Max longitudinal particle position of the beam */
-    amrex::Real m_radius; /**< Radius of the can beam */
+    amrex::Real m_radius {std::numeric_limits<amrex::Real>::infinity()}; /**< Radius of the beam */
     amrex::RealVect m_position_mean {0., 0., 0.}; /**< mean position of the beam */
     amrex::Real m_min_density {0.}; /**< minimum density at which beam particles are generated */
     amrex::IntVect m_random_ppc {0, 0, 0}; /**< if the cell position is random in each direction */

diff --git a/src/particles/beam/BeamParticleContainer.cpp b/src/particles/beam/BeamParticleContainer.cpp
@@ -109,6 +109,7 @@ BeamParticleContainer::InitData (const amrex::Geometry& geom)
         amrex::Real zmax = std::numeric_limits<amrex::Real>::infinity();
         std::string profile = "gaussian";
         queryWithParser(pp, "profile", profile);
+        queryWithParser(pp, "radius", m_radius);
         if (profile == "can") {
             can = true;
             getWithParser(pp, "zmin", zmin);
@@ -162,7 +163,7 @@ BeamParticleContainer::InitData (const amrex::Geometry& geom)
 
         const GetInitialMomentum get_momentum(m_name);
         InitBeamFixedWeight(m_num_particles, get_momentum, pos_mean_x, pos_mean_y, pos_mean_z,
-                            m_position_std, m_total_charge, m_z_foc, m_do_symmetrize, can, zmin, zmax);
+                            m_position_std, m_total_charge, m_z_foc, m_do_symmetrize, can, zmin, zmax, m_radius);
         m_total_num_particles = getBeamInitSlice().size();
 
     } else if (m_injection_type == "from_file") {

diff --git a/src/particles/beam/BeamParticleContainerInit.cpp b/src/particles/beam/BeamParticleContainerInit.cpp
@@ -313,7 +313,8 @@ InitBeamFixedWeight (int num_to_add,
                      const amrex::Real total_charge,
                      const amrex::Real z_foc,
                      const bool do_symmetrize,
-                     const bool can, const amrex::Real zmin, const amrex::Real zmax)
+                     const bool can, const amrex::Real zmin, const amrex::Real zmax,
+                     const amrex::Real radius)
 {
     HIPACE_PROFILE("BeamParticleContainer::InitParticles()");
     using namespace amrex::literals;
@@ -355,13 +356,14 @@ InitBeamFixedWeight (int num_to_add,
                 amrex::Real u[3] = {0.,0.,0.};
                 get_momentum(u[0],u[1],u[2], engine, z, duz_per_uz0_dzeta);
 
-                // Propagate each electron ballistically for z_foc
-                x -= z_foc*u[0]/get_momentum.m_u_mean[2];
-                y -= z_foc*u[1]/get_momentum.m_u_mean[2];
-
                 const amrex::Real z_central = z + z_mean;
                 int valid_id = pid;
-                if (z_central < zmin || z_central > zmax) valid_id = -1;
+                if (z_central < zmin || z_central > zmax ||
+                    x*x + y*y > radius*radius) valid_id = -1;
+
+                // Propagate each electron ballistically for z_foc
+                x -= z_foc*u[0]/u[2];
+                y -= z_foc*u[1]/u[2];
 
                 const amrex::Real cental_x_pos = pos_mean_x(z_central);
                 const amrex::Real cental_y_pos = pos_mean_y(z_central);