added sources

docs/source/userguide/sources.rst

@@ -5,4 +5,62 @@ Sources
 =======
 
 
-WIP
+Volumetric sources
+------------------
+
+Volumetric sources can be set in a simulation by using the :class:`festim.Source` class.
+
+.. code:: python
+
+    import festim as F
+
+    my_model = F.Simulation()
+
+    my_model.sources = [
+        F.Source(value=1e20, volume=1, field=0),
+        F.Source(value=1e19 * F.x, volume=2, field=0),
+        ]
+
+For more information, see :class:`festim.Source`.
+
+Implantation flux
+-----------------
+
+Hydrogen implanted in a material can be simulated by a gaussian-shaped volumetric source with the :class:`festim.ImplantationFlux` class.
+
+.. code:: python
+
+    import festim as F
+
+    my_model = F.Simulation()
+
+    my_model.sources = [
+        F.ImplantationFlux(
+            flux=1e20,
+            imp_depth=1e-9,
+            width=1e-9,
+            volume=1,
+            ),
+        ]
+
+This class is used in `this tutorial <https://github.com/festim-dev/FESTIM-workshop/blob/main/tasks/task2.ipynb>`_.
+
+
+Radioactive decay
+-----------------
+
+Radioactive decay can be simulated by a volumetric source with the :class:`festim.RadioactiveDecay` class.
+
+.. code:: python
+
+    import festim as F
+
+    my_model = F.Simulation()
+
+    my_model.sources = [
+        F.RadioactiveDecay(
+            decay_constant=1.78e-9,
+            volume=1,
+            fields="all",
+            ),
+        ]