Grounded wall at the end of TPC II, with one Field/Fat Anode Wire receded (meaning two out of last 3 fat wires removed)
Wall extends 1.25 mm abowe the cathode wire grid and is 2.5 mm away from the last cathode wire.

Below is the same as above but with the field wire diameter 75 μm instead of nominal 125 μm (mixup during wiring)

Below is the no wall situation for comparison