Efficient and powerful generation of XUV radiation with a femtosecond KrF laser system

M2=4.5), which is approximately valid here, the intensity In(1) of the n-harmonic is given by Inco = const lxl2N2L2 (Iw)nsinc2AkL/2, where % is the susceptibility per atom or ion, N the corresponding density and AkL the total phase mismatch. The wave vector mismatch Ak = knw - nkw = Akgeom + NatAkat + NionAkion + NeiectrAkeiectr thereby consists of dispersive contributions Akat, Ak¡on and Akeiectr due to atoms, ions and electrons with corresponding densities Nat, Nion, Neiectr. The geometrical contribution due to the focussing is given by Akgeom = 2(n-l)/b.