Reviewed the possible solutions to reduce the stress in the PF 4 coil and provide shape control in the PF coils.  The plan is to provide spring loaded clamps similar to the current design to provide a force high enough to overcome magnetic forces to keep coils centered through normal operating temperature scenarios.  Requires analysis by EA group to provide spring sizing.

Provided analysis of the deflections of the OTF without the inner link and with the outer ring modified with one end fixed, other end pinned connections.  Indicates that inner ring is not required if compliant link (aka radius rods) are used to carry some of the OOP loads.  

The plan forward:

  1. Support the PF4/5 off the existing PF4,5 supports and use 6 to 12 columns.  

2. More connections from the PF4-5 coils to limit PF 4 stress.  

3. The OTF will be support using the outer ring (1 fixed, 1 pinned end) and compliant links to clevis, which will not be modified.

Han presented analysis using one of the larger scenarios, no. 79 on the OTF using the outer ring. Scenario 79: Utheta=2.7mm (0.1”), shear in the epoxy between coil turns is 10.7MPa (1551 psi).  Load in radius rod: 32KN (7.3klbs).  Further work needs to be done with the remaining scenarios but the initial results look good.

Dynamic stresses (from an outer limiter disruption) in the passive plate copper are 90 t0 135 MPa (13 to 20 ksi) and 600 MPa (87 ksi) in the fasteners.  The fasteners will need to be replaced with higher strength fasteners.  

Using the VDE disruption (plasma 1 to plasma 5) stresses in the passive plate brackets are much higher at 2 GPa (290 ksi) which is well beyond conventional materials.  Neumeyer to verify this disruption as a realistic scenario.  The effort to mitigate against this scenario would be significant to severe, possibly requiring a material change of the passive plates.

Let a discussion on the potential heating issues from the upgrade on the RF Limiter boron nitride tiles.  While the tiles may increase in temperature and potenitally overheat Menard believes that we may be able to control heating by the plasma to limiter spacing (10-12 cm).  It's not clear at this time that the plasma would have to be run close to the limiter and overheat the tiles.  The decision forward is that no action is required at this time.