diff --git a/FDTD/extensions/operator_ext_cylinder.cpp b/FDTD/extensions/operator_ext_cylinder.cpp
index 13f48d5..a7e9a1d 100644
--- a/FDTD/extensions/operator_ext_cylinder.cpp
+++ b/FDTD/extensions/operator_ext_cylinder.cpp
@@ -47,7 +47,7 @@ bool Operator_Ext_Cylinder::BuildExtension()
 
 	//if r=0 is not included -> obviously no special treatment for r=0
 	//if alpha direction is not closed, PEC-BC at r=0 necessary and already set...
-	if ((CC_R0_included==false) || (CC_closedAlpha==false))
+	if (CC_R0_included==false)
 		return true;
 
 	vv_R0 = new FDTD_FLOAT[m_Op->GetOriginalNumLines(2)];
diff --git a/FDTD/operator_cylinder.cpp b/FDTD/operator_cylinder.cpp
index 392c391..97accd6 100644
--- a/FDTD/operator_cylinder.cpp
+++ b/FDTD/operator_cylinder.cpp
@@ -209,6 +209,7 @@ bool Operator_Cylinder::SetupCSXGrid(CSRectGrid* grid)
 		CC_closedAlpha=false;
 	}
 
+	CC_R0_included = false;
 	if (grid->GetLine(0,0)<0)
 	{
 		cerr << "Operator_Cylinder::SetupCSXGrid: r<0 not allowed in Cylinder Coordinates!!!" << endl;
@@ -218,9 +219,42 @@ bool Operator_Cylinder::SetupCSXGrid(CSRectGrid* grid)
 	else if (grid->GetLine(0,0)==0.0)
 	{
 		cout << "Operator_Cylinder::SetupCSXGrid: r=0 included..." << endl;
-		CC_R0_included= true;  //also needed for correct ec-calculation
+		CC_R0_included = CC_closedAlpha;  //needed for correct ec-calculation, deactivate if closed cylinder is false... --> E_r = 0 anyways
 	}
 
+#ifdef MPI_SUPPORT
+		// Setup an MPI split in alpha direction for a closed cylinder
+		CC_MPI_Alpha = false;
+	if ((m_NeighborUp[1]>=0) || (m_NeighborDown[1]>=0)) //check for MPI split in alpha direction
+	{
+		double minmaxA = 2*PI;// fabs(m_OrigDiscLines[1][m_OrigNumLines[1]-1]-m_OrigDiscLines[1][0]);
+		if (fabs(minmaxA-2*PI) < OPERATOR_CYLINDER_CLOSED_ALPHA_THRESHOLD) //check for closed alpha MPI split
+		{
+			CC_MPI_Alpha = true;
+			if (m_OrigDiscLines[0][0]==0)
+			{
+				cerr << "Operator_Cylinder::SetupCSXGrid: Error: MPI split in alpha direction for closed cylinder including r==0 is currently not supported! Exit!" << endl;
+				exit(-2);
+			}
+
+			if (m_NeighborUp[1]<0) //check if this process is at the alpha-end
+			{
+				grid->SetLine(1,alphaNum-1,2*PI+m_OrigDiscLines[1][0]);
+				grid->AddDiscLine(1,2*PI+m_OrigDiscLines[1][1]);
+
+				SetNeighborUp(1,m_ProcTable[m_ProcTablePos[0]][0][m_ProcTablePos[2]]);
+			}
+
+			if (m_NeighborDown[1]<0) //check if this process is at the alpha-start
+			{
+				SetNeighborDown(1,m_ProcTable[m_ProcTablePos[0]][m_SplitNumber[1]-1][m_ProcTablePos[2]]);
+			}
+
+			//Note: the process table will not reflect this up/down neighbors necessary for a closed cylinder
+		}
+	}
+#endif
+
 	if (Operator_Multithread::SetupCSXGrid(grid)==false)
 		return false;
 
diff --git a/FDTD/operator_cylinder.h b/FDTD/operator_cylinder.h
index 56d2807..8c5a9d2 100644
--- a/FDTD/operator_cylinder.h
+++ b/FDTD/operator_cylinder.h
@@ -30,6 +30,7 @@ all special cases e.g. a closed alpha mesh or an included r=0 case is treated by
 class Operator_Cylinder : public Operator_Multithread
 {
 	friend class Operator_CylinderMultiGrid;
+	friend class Operator_Ext_Cylinder;
 public:
 	static Operator_Cylinder* New(unsigned int numThreads = 0);
 	virtual ~Operator_Cylinder();
@@ -86,6 +87,10 @@ protected:
 
 	bool CC_closedAlpha;
 	bool CC_R0_included;
+
+#ifdef MPI_SUPPORT
+	bool CC_MPI_Alpha;
+#endif
 };
 
 #endif // OPERATOR_CYLINDER_H