A radially movable detector located just below the outer midplane of the Tokamak Fusion Test Reactor (TFTR) [inPlasmaPhysicsandControlledNuclearFusionResearch, 1988 (International Atomic Energy Agency, Vienna, 1989), Vol. 1, p. 27] has been used to study the confinement of charged fusion products (CFP’s). The scrape‐off length of escaping CFP flux was measured using perturbative techniques based on shadowing the detector with different obstacles. Experimental results indicate the presence of a diffusive process for trapped particles. Derived diffusion step sizes were found to be in excellent agreement with those expected from toroidal magnetic field (TF) stochastic ripple diffusion.