152 PF coil

process/pfcoil.py

@@ -547,7 +547,7 @@ def pfcoil(self):
                     dz = 0.5e0 * (
                         bv.hmax * (1.0e0 - pfv.ohhghf) + bv.tfcth + 0.1e0
                     )  # ???
-                    area = 4.0e0 * dx * dz
+                    area = 4.0e0 * dx * dz * pfv.pf_current_safety_factor
 
                     # Number of turns
                     # CPTDIN[i] is the current per turn (input)
@@ -576,7 +576,10 @@ def pfcoil(self):
                 else:
                     # Other coils. N.B. Current density RJCONPF[i] is defined in
                     # routine INITIAL for these coils.
-                    area = abs(pfv.ric[i] * 1.0e6 / pfv.rjconpf[i])
+                    area = (
+                        abs(pfv.ric[i] * 1.0e6 / pfv.rjconpf[i])
+                        * pfv.pf_current_safety_factor
+                    )
 
                     pfv.turns[i] = abs((pfv.ric[i] * 1.0e6) / pfv.cptdin[i])
                     aturn[i] = area / pfv.turns[i]
@@ -675,12 +678,15 @@ def pfcoil(self):
 
                 if pfv.ipfres == 0:
                     # Superconducting coil
-                    # Previous assumptions: 500 MPa stress limit with 2/3 of the force
-                    # supported in the outer (steel) case.
-                    # Now, 500 MPa replaced by sigpfcalw, 2/3 factor replaced by sigpfcf
+                    # Updated assumptions: 500 MPa stress limit with all of the force
+                    # supported in the conduit (steel) case.
+                    # Now, 500 MPa replaced by sigpfcalw, sigpfcf now defaultly set to 1
 
                     areaspf = pfv.sigpfcf * forcepf / (pfv.sigpfcalw * 1.0e6)
 
+                    # Thickness of hypothetical steel casing assumed to encase the PF
+                    # winding pack; in reality, the steel is distributed
+                    # throughout the conductor. Issue #152
                     # Assume a case of uniform thickness around coil cross-section
                     # Thickness found via a simple quadratic equation
 
@@ -2314,15 +2320,15 @@ def outpf(self):
         op.osubhd(self.outfile, "Geometry of PF coils, central solenoid and plasma:")
         op.write(
             self.outfile,
-            "coil\t\t\tR(m)\t\tZ(m)\t\tdR(m)\t\tdZ(m)\t\tturns\t\tsteel thickness(m)",
+            "coil\t\t\tR(m)\t\tZ(m)\t\tdR(m)\t\tdZ(m)\t\tturns",
         )
         op.oblnkl(self.outfile)
 
         # PF coils
         for k in range(pf.nef):
             op.write(
                 self.outfile,
-                f"PF {k}\t\t\t{pfv.rpf[k]:.2e}\t{pfv.zpf[k]:.2e}\t{pfv.rb[k]-pfv.ra[k]:.2e}\t{abs(pfv.zh[k]-pfv.zl[k]):.2e}\t{pfv.turns[k]:.2e}\t{pfv.pfcaseth[k]:.2e}",
+                f"PF {k}\t\t\t{pfv.rpf[k]:.2e}\t{pfv.zpf[k]:.2e}\t{pfv.rb[k]-pfv.ra[k]:.2e}\t{abs(pfv.zh[k]-pfv.zl[k]):.2e}\t{pfv.turns[k]:.2e}",
             )
 
         for k in range(pf.nef):

source/fortran/iteration_variables.f90

@@ -2230,7 +2230,7 @@ end subroutine set_itv_98
 
   !---------------------------------
 
-  
+
 
   !---------------------------------
 
@@ -4060,7 +4060,7 @@ subroutine loadxc
            case (99);
            case (100);
            case (101);
-           case (102); 
+           case (102);
            case (103);  xcm(i) = itv_103()
            case (104);  xcm(i) = itv_104()
            case (105);  xcm(i) = itv_105()
@@ -4327,7 +4327,7 @@ subroutine convxc(xc,nn)
            case (99);
            case (100);
            case (101);
-           case (102);  
+           case (102);
            case (103);  call set_itv_103(ratio)
            case (104);  call set_itv_104(ratio)
            case (105);  call set_itv_105(ratio)

source/fortran/pfcoil_variables.f90

@@ -213,6 +213,10 @@ module pfcoil_variables
   real(dp) :: oh_steel_frac
   !! central solenoid steel fraction (`iteration variable 122`)
 
+  real(dp) :: pf_current_safety_factor
+  !! Ratio of permissible PF coil conductor current density to critical conductor
+  !! current density based on short-sample DC measurements
+
   real(dp), dimension(ngc2) :: pfcaseth
   !! steel case thickness for PF coil i (m)
 
@@ -443,6 +447,7 @@ subroutine init_pfcoil_variables
     nohc = 0
     ohhghf = 0.71D0
     oh_steel_frac = 0.5D0
+    pf_current_safety_factor = 1.0D0
     pfcaseth = 0.0D0
     pfclres = 2.5D-8
     pfmmax = 0.0D0
@@ -466,7 +471,7 @@ subroutine init_pfcoil_variables
       7.0D0, 7.0D0, 7.0D0, 7.0D0, 7.0D0, 7.0D0, 7.0D0/)
     s_tresca_oh = 0.0D0
     sigpfcalw = 500.0D0
-    sigpfcf = 0.666D0
+    sigpfcf = 1.0D0
     sxlg = 0.0D0
     tmargoh = 0.0D0
     turns = 0.0D0

tests/regression/scenarios/large-tokamak/IN.DAT

@@ -581,6 +581,9 @@ fcuohsu = 0.70
 * ITER Nb3Sn parameterisation
 isumatoh = 1
 
+* Fraction of JxB force supported by PF coil case
+sigpfcf = 0.666
+
 * TF Coil *
 ***********