BOND FORMULA: V(gap) = -A * exp(-2*kappa_kink*gap)
kappa_kink = sqrt(1 - omega^2_kink) = 0.676
omega^2_kink = 0.544 (kink bound mode of poloidal torus)
Casimir round-trip: factor of 2 in exponent (there and back)

R_maj=6 data (clean, no periodic image artifact):
  gap=12: V=-0.079 (well bottom)
  gap=14: V=-0.002
  gap=16: V=-0.0002
  Measured kappa=1.30, predicted 2*0.676=1.35 (4% match)

R_maj=8 was contaminated: V(gap=12)=V(gap=20) from periodic images.
