Di Mitri, S. MOP053 electron emittance linac brightness quadrupole 2015 2015-12 Intra-beam scattering (IBS) of a high brightness electron beam in a linac has been studied* analytically, and the expectations found to be in reasonable agreement with particle tracking results from the Elegant code. It comes out that, under standard conditions for a linac driving a free electron laser, IBS plays no significant role in the development of microbunching instability. A partial damping of the instability is envisaged, however, when IBS is enhanced either with dedicated magnetic insertions, or in the presence of an electron beam charge density at least 4 times larger than that produced by present photo-injectors.