bugfix related to charge

Author: giadarol

testing/interactive-tests/PyCUDA_longitudinal.ipynb

@@ -327,7 +327,7 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython2",
-   "version": "2.7.10"
+   "version": "2.7.6"
   }
  },
  "nbformat": 4,

trackers/simple_long_tracking.py

@@ -197,7 +197,7 @@ def track_with_dispersion(self, beam):
         beam.y += self.D_y*beam.dp
 
     def track_without_dispersion(self, beam):
-        amplitude = e*self.voltage / (beam.beta*c)
+        amplitude = beam.charge*self.voltage / (beam.beta*c)
         phi = (self.harmonic * (2*np.pi*beam.z/self.circumference)
                + self.phi_offset + self._phi_lock)