Progress in FWSD non-linear effects with XRLs S.J. Topping, R. Keenan, C.L.S. Lewis, R.M.N. O’Rourke, A.G. MacPhee, S. Dobosz, G.J. Tallents, M. Notely et D. Neely J. Phys. IV France, 11 PR2 (2001) Pr2-487-Pr2-490 DOI: 10.1051/jp4:2001293