Ensure njit is used in plasma fields (#4172)

Author: chris-ashe

process/models/physics/plasma_fields.py

@@ -91,7 +91,7 @@ def calculate_surface_averaged_poloidal_field(
         return b_plasma_toroidal_on_axis * (ff1 + ff2) / (2.0 * np.pi * qbar)
 
     @staticmethod
-    @nb.jit(cache=True)
+    @nb.njit(cache=True)
     def calculate_plasma_inboard_toroidal_field(
         b_plasma_toroidal_on_axis: float,
         rmajor: float,
@@ -117,7 +117,7 @@ def calculate_plasma_inboard_toroidal_field(
         return rmajor * b_plasma_toroidal_on_axis / (rmajor - rminor)
 
     @staticmethod
-    @nb.jit(cache=True)
+    @nb.njit(cache=True)
     def calculate_plasma_outboard_toroidal_field(
         b_plasma_toroidal_on_axis: float,
         rmajor: float,
@@ -143,7 +143,7 @@ def calculate_plasma_outboard_toroidal_field(
         return rmajor * b_plasma_toroidal_on_axis / (rmajor + rminor)
 
     @staticmethod
-    @nb.jit(cache=True)
+    @nb.njit(cache=True)
     def calculate_toroidal_field_profile(
         b_plasma_toroidal_on_axis: float,
         rmajor: float,
@@ -178,7 +178,7 @@ def calculate_toroidal_field_profile(
         return rmajor * b_plasma_toroidal_on_axis / rho
 
     @staticmethod
-    @nb.jit(cache=True)
+    @nb.njit(cache=True)
     def calculate_total_magnetic_field(
         b_plasma_toroidal: float, b_plasma_poloidal: float
     ) -> float: