diff --git a/Source/Fields/LMCCylindricalCavity.cc b/Source/Fields/LMCCylindricalCavity.cc
index 7f1864d4..6a645fdc 100644
--- a/Source/Fields/LMCCylindricalCavity.cc
+++ b/Source/Fields/LMCCylindricalCavity.cc
@@ -17,7 +17,9 @@ namespace locust
         fProbeGain( {1., 1., 1.}),
         fCavityProbeZ( {0., 0., 0.} ),
         fCavityProbeRFrac( {0.5, 0.5, 0.5} ),
-        fCavityProbeTheta( {0.0, 0.0, 0.0} )
+        fCavityProbeTheta( {0.0, 0.0, 0.0} ),
+        fCaterpillarCavity( false ),
+        fApplyDopplerShift( true )
         {}
 
     CylindricalCavity::~CylindricalCavity() {}
@@ -33,6 +35,16 @@ namespace locust
             return false;
         }
 
+        if( aParam.has( "caterpillar-cavity" ) )
+        {
+            fCaterpillarCavity = aParam["caterpillar-cavity"]().as_bool();
+        }
+
+        if( aParam.has( "apply-doppler-shift" ) )
+        {
+            fApplyDopplerShift = aParam["apply-doppler-shift"]().as_bool();
+        }
+
         if( aParam.has( "cavity-radius" ) )
         {
             SetDimR( aParam["cavity-radius"]().as_double() );
@@ -227,11 +239,16 @@ namespace locust
         double vz = tKassParticleXP[5];
         double term1 = fFieldCore->GetBesselNKPrimeZeros(l,m) / GetDimR();
         double term2 = n * LMCConst::Pi() / GetDimL();
+        if ( fCaterpillarCavity )
+        {
+            // Assume n-channels is the same as the number of etalon sections:
+            term2 *= GetNChannels();
+        }
         double lambda = 1. / pow( 1. / 4. / LMCConst::Pi() / LMCConst::Pi() * ( term1*term1 + term2*term2 ), 0.5);
         double lambda_c = 2 * LMCConst::Pi() * GetDimR() / fFieldCore->GetBesselNKPrimeZeros(l,m);
         double vp = LMCConst::C() / pow( 1. - lambda*lambda/lambda_c/lambda_c, 0.5 );
         double dopplerShift = 0.;
-        if (vp > 0.) dopplerShift = vz / vp;
+        if ((vp > 0.) && (fApplyDopplerShift)) dopplerShift = vz / vp;
 	    freqPrime.push_back( ( 1. + dopplerShift ) * tKassParticleXP[7] );
         return freqPrime;
     }
@@ -325,7 +342,23 @@ namespace locust
         std::vector<double> tEFieldAtProbe;
         for (unsigned index=0; index<GetNChannels(); index++)
         {
-            tEFieldAtProbe.push_back( NormalizedEFieldMag(GetNormalizedModeField(l,m,n,tProbeLocation[index],0,teMode)) );
+            if ( !fCaterpillarCavity )
+            {
+                tEFieldAtProbe.push_back( NormalizedEFieldMag(GetNormalizedModeField(l,m,n,tProbeLocation[index],0,teMode)) );
+            }
+            else
+            {
+                // Assume 1 channel per etalon section:
+                int indexSubCavity = (int)(( tKassParticleXP[2] + GetDimL()/2. ) * GetNChannels() / GetDimL());
+                if ( indexSubCavity == index ) // If the electron is in the etalon section where the probe is:
+                {
+                    tEFieldAtProbe.push_back( NormalizedEFieldMag(GetNormalizedModeField(l,m,n,tProbeLocation[index],0,teMode)) );
+                }
+                else
+                {
+                    tEFieldAtProbe.push_back( 0. );
+                }
+            }
         }
 
         return {fProbeGain[0] * tEFieldAtProbe[0], fProbeGain[1] * tEFieldAtProbe[1], fProbeGain[2] * tEFieldAtProbe[2]};
diff --git a/Source/Fields/LMCCylindricalCavity.hh b/Source/Fields/LMCCylindricalCavity.hh
index 9d39180b..89a7f65f 100644
--- a/Source/Fields/LMCCylindricalCavity.hh
+++ b/Source/Fields/LMCCylindricalCavity.hh
@@ -86,6 +86,8 @@ namespace locust
             std::vector<double> fCavityProbeRFrac;
             std::vector<double> fCavityProbeTheta;
             std::vector<double> fProbeGain;
+            bool fCaterpillarCavity;
+            bool fApplyDopplerShift;
 
     };
 
diff --git a/Source/Fields/LMCField.cc b/Source/Fields/LMCField.cc
index 8fab166c..420ef717 100644
--- a/Source/Fields/LMCField.cc
+++ b/Source/Fields/LMCField.cc
@@ -16,8 +16,9 @@ namespace locust
         fCentralFrequency(1.63e11),
 		fAvgDotProductFactor( 0. ),
         fNModes( 2 ),
+        fNChannels( 1 ),
         fbMultiMode( false ),
-		fTM111( false ),
+        fTM111( false ),
         fR( 0.18 ),
         fL( 3.0 ),
         fX( 0.010668 ),
diff --git a/Source/Fields/LMCModeMapCavity.cc b/Source/Fields/LMCModeMapCavity.cc
index 3ab5455d..1d00c877 100644
--- a/Source/Fields/LMCModeMapCavity.cc
+++ b/Source/Fields/LMCModeMapCavity.cc
@@ -116,7 +116,7 @@ namespace locust
                 std::string token;
                 std::stringstream ss(lineContent);
                 int wordCount = 0;
-		double r, theta, z;
+                double r, theta, z;
                 int i,j,k;
                 double Erho,Etheta;
                 double Ex, Ey, Ez;
@@ -124,19 +124,19 @@ namespace locust
                 {
                     if (wordCount == 0)
                     {
-			r = std::stod(token);
+                        r = std::stod(token);
                         i = (int)((r-fDim1_min)/(fDim1_max-fDim1_min)*(fnPixel1)); // var1 position
-		    }
+                    }
                     else if (wordCount == 1) 
-		    {
-			theta = std::stod(token);
-			j = (int)((theta-fDim2_min)/(fDim2_max-fDim2_min)*(fnPixel2)); // var2 position
-		    }
+                    {
+                        theta = std::stod(token);
+                        j = (int)((theta-fDim2_min)/(fDim2_max-fDim2_min)*(fnPixel2)); // var2 position
+                    }
                     else if (wordCount == 2)
-		    {
-			z = std::stod(token);
-			k = (int)((z-fDim3_min)/(fDim3_max-fDim3_min)*(fnPixel3)); // var3 position
-		    }
+                    {
+                        z = std::stod(token);
+                        k = (int)((z-fDim3_min)/(fDim3_max-fDim3_min)*(fnPixel3)); // var3 position
+                    }
                     else if (wordCount == 3) Ex = std::stod(token); // mode E field value
                     else if (wordCount == 4) Ey = std::stod(token); // mode E field value
                     else if (wordCount == 5) Ez = std::stod(token); // mode E field value
@@ -148,10 +148,10 @@ namespace locust
                     ++wordCount;
                 }
 
-		if ((i==fnPixel1) or (j==fnPixel2) or (k==fnPixel3))
-		{
-			continue;
-		}
+                if ((i==fnPixel1) or (j==fnPixel2) or (k==fnPixel3))
+                {
+                    continue;
+                }
                 if ((i>=fnPixel1) or (j>=fnPixel2) or (k>=fnPixel3))
                 {   
                     LERROR(lmclog,"Imported mode map dimensions don't agree with those in \"" << aFilename <<".\" Double check dim[1,2,3]-max.");
@@ -159,26 +159,27 @@ namespace locust
                 }   
 
                 //Must convert E field from cartesian coordinates to cylindrical coordinates
-		if(r<1.e-10)
-		{
-		    Erho = 0.;
-		    Etheta = 0.;
-		}
-		else
-		{
+                if(r<1.e-10)
+                {
+                    Erho = 0.;
+                    Etheta = 0.;
+                }
+                else
+                {
                     Erho = ((Ex * r*cos(theta)) + Ey * r*sin(theta)) / r;
-		    Etheta = ((Ey * r*cos(theta)) - Ex * r*sin(theta)) / r;
-		}
+                    Etheta = ((Ey * r*cos(theta)) - Ex * r*sin(theta)) / r;
+                }
 
                 std::vector E_input = {Erho,Etheta,Ez};
                 fModeMapTE_E[i][j][k] = E_input;
-//              printf("read var1 is %g, var2 is %g, E is %g\n", fModeMapTE_E.back()[0], fModeMapTE_E.back()[1], fModeMapTE_E.back()[2]);
+                //printf("read var1 is %g, var2 is %g, E is %g\n", fModeMapTE_E.back()[0], fModeMapTE_E.back()[1], fModeMapTE_E.back()[2]);
+
             }
         }
 
         modeMapFile.close();
 
-	//Reset dimensions from import file to actual cavity dimensions in case they don't match up
+        //Reset dimensions from import file to actual cavity dimensions in case they don't match up
         MatchCavityDimensions(aParam);
 
         return true;