Adding a ThermalCXRate coefficient and associated interface.

cherab/core/atomic/interface.pxd

@@ -28,6 +28,8 @@ cdef class AtomicData:
 
     cpdef RecombinationRate recombination_rate(self, Element ion, int charge)
 
+    cpdef ThermalCXRate thermal_cx_rate(self, Element donor_ion, int donor_charge, Element receiver_ion, int receiver_charge)
+
     cpdef list beam_cx_pec(self, Element donor_ion, Element receiver_ion, int receiver_charge, tuple transition)
 
     cpdef BeamStoppingRate beam_stopping_rate(self, Element beam_ion, Element plasma_ion, int charge)

cherab/core/atomic/interface.pyx

@@ -38,6 +38,9 @@ cdef class AtomicData:
     cpdef RecombinationRate recombination_rate(self, Element ion, int charge):
         raise NotImplementedError("The recombination_rate() virtual method is not implemented for this atomic data source.")
 
+    cpdef ThermalCXRate thermal_cx_rate(self, Element donor_ion, int donor_charge, Element receiver_ion, int receiver_charge):
+        raise NotImplementedError("The thermal_cx_rate() virtual method is not implemented for this atomic data source.")
+
     cpdef list beam_cx_pec(self, Element donor_ion, Element receiver_ion, int receiver_charge, tuple transition):
         """
         Returns a list of applicable charge exchange emission rates in W.m^3.

cherab/core/atomic/rates.pxd

@@ -29,6 +29,11 @@ cdef class RecombinationRate:
     cpdef double evaluate(self, double density, double temperature) except? -1e999
 
 
+cdef class ThermalCXRate:
+
+    cpdef double evaluate(self, double density, double temperature) except? -1e999
+
+
 cdef class _PECRate:
     cpdef double evaluate(self, double density, double temperature) except? -1e999
 

cherab/core/atomic/rates.pyx

@@ -64,6 +64,28 @@ cdef class RecombinationRate:
         raise NotImplementedError("The evaluate() virtual method must be implemented.")
 
 
+cdef class ThermalCXRate:
+    """
+    Effective charge exchange rate between two ions.
+    """
+
+    def __call__(self, double density, double temperature):
+        """Returns an effective charge exchange rate coefficient at the specified plasma conditions.
+
+        This function just wraps the cython evaluate() method.
+        """
+        return self.evaluate(density, temperature)
+
+    cpdef double evaluate(self, double density, double temperature) except? -1e999:
+        """Returns an effective charge exchange rate coefficient at the specified plasma conditions.
+
+        :param temperature: Electron temperature in eV.
+        :param density: Electron density in m^-3
+        :return: The effective charge exchange rate in m^-3.
+        """
+        raise NotImplementedError("The evaluate() virtual method must be implemented.")
+
+
 cdef class _PECRate:
     """
     Photon emissivity coefficient base class.