CAS, Inst High Energy Phys, Beijing 100039, Peoples R China
; CAEP, Inst Fluid Phys, Mianyang 621900, Peoples R China
According to characteristics of Linear Induction Accelerator( LIA), the model of cylindrically symmetric DC beams is adopted in this paper. The differential equation of RMS emittance growth is derived. One of the emittance growth mechanism is presented,which assumes that the beam profile will not stop evolving unless it has Gaussian distribution due to non-linearity during beam transportation. Consequently, the emittance growth is calculated from K-V distribution to Gaussian distribution, and the control methods of emittance growth is discussed.