[WIP] Atomic collision model

src/collision/atomic.h

@@ -0,0 +1,85 @@
+#ifndef _atomic_h_
+#define _atomic_h_
+#include "collision.h"
+
+typedef struct atomic_properties {
+  float alpha_m2;    // alpha^-2 = 2*Ry/me c^2
+  float Nca02;       // n0 c a_0^2 has units of 1/time
+
+  // Atomic data routines. They are denoted by _ab_xx where a and b are the
+  // species [ e: electrons, z: primary ions, z1: parent ions ] and xx are the processes:
+  //  el : elastic scattering
+  //  cx : charge exchange (implemented as backward-dominated scattering)
+  //  ex : excitation (inelastic scattering)
+  //  in : ionization
+  //  rx : recombination
+  // Note that elastic scattering cross-sections only make sense when z=0, such
+  // that the primary ion is actually a neutral atom. Otherwise, elastic
+  // collisions will likely be dominated by Coulomb collisions and a different
+  // collisional model should be applied.
+
+  // Cross sections. Each should take on input the collision energy in units of
+  // Ry and return the cross-section in units of a0^2.
+  float (*sigma_pt_el)(float E);
+  float (*sigma_pt_cx)(float E);
+  float (*sigma_pt_ex)(float E);
+  float (*sigma_et_el)(float E);
+  float (*sigma_et_ex)(float E);
+  float (*sigma_et_in)(float E);
+  float (*sigma_ep_rx)(float E);
+  float (*sigma_tt_el)(float E);
+  float (*sigma_tt_ex)(float E);
+
+  // Delta = tan(theta/2). Each should take on input the collision energy.
+  float (*delta_pt_el)(rng_t* rng, float E);
+  float (*delta_pt_cx)(rng_t* rng, float E);
+  float (*delta_et_el)(rng_t* rng, float E);
+  float (*delta_tt_el)(rng_t* rng, float E);
+
+  // Gamma is the coefficient of restitution for inelastic processes, defined
+  // by gamma = sqrt(KE'/KE) where KE' is the post-collision energy and KE
+  // is the collision energy. Each should take on input the collision energy.
+  float (*gamma_pt_ex)(rng_t* rng, float E);
+  float (*gamma_et_ex)(rng_t* rng, float E);
+  float (*gamma_tt_ex)(rng_t* rng, float E);
+
+  // For ionization, we also set the secondary energy (in Ry)
+  float (*gamma_et_in)(rng_t* rng, float Eprimary, float *Esecondary);
+
+} atomic_properties_t;
+
+enum atomic_processes {
+  parent_target_elastic          = 1 << 0,
+  parent_target_charge_exchange  = 1 << 1,
+  parent_target_inelastic        = 1 << 2,
+  electron_target_elastic        = 1 << 3,
+  electron_target_inelastic      = 1 << 4,
+  electron_target_ionization     = 1 << 5,
+  electron_parent_recombination  = 1 << 6,
+  target_target_elastic          = 1 << 7,
+  target_target_inelastic        = 1 << 8,
+  three_body_recombination       = 1 << 9,
+  all_atomic_processes           = 0xFFFF
+};
+
+BEGIN_C_DECLS
+
+collision_op_t *
+append_atomic_collision_operators( /**/  unsigned int                   processes,
+                                   /**/  species_t           * RESTRICT electron,
+                                   /**/  species_t           * RESTRICT target,
+                                   /**/  species_t           * RESTRICT parent,
+                                   const atomic_properties_t * RESTRICT base,
+                                   /**/  field_array_t       * RESTRICT fa,
+                                   /**/  rng_pool_t          * RESTRICT rp,
+                                   /**/  collision_op_t     **          cop_list,
+                                   const double                         Na02,
+                                   const double                         alpha,
+                                   const int                            interval,
+                                   const double                         sample,
+                                   const double                         Emax
+                                 );
+
+END_C_DECLS
+
+#endif /* _atomic_h_ */