Two-dimensional performance of uniform irradiation with the use of a concentricity deviation lens array and partially coherent light

Abstract

A method of employing a lens array (LA) and partially coherent light (PCL) is presented for uniform irradiation on targets in inertial confinement fusion. Quasi-near field spots with a profile of sharp edge and flat top can be obtained with an LA, while the spatial coherence of the incidence beam is reduced by PCL. An appropriate concentricity deviation (CD) of LA results in the superposition of beamlets at the focus dislocated by a small amount each other and the CD and PCL reduce the fringe separations, thus the interference fringes become denser and the small-scale intensity non-uniformity of intensity distribution is suppressed. Based on the generalized diffraction integral theory, the intensity distribution of a Gaussian Schell Beam (GSB), point focused by an LA and a spherical lens is investigated in detail by two-dimensional simulation. And irradiation uniformity effects are compared with coherent light and partially coherent light after the LA. Numerical results indicate that using an appropriate CD and moving the target slightly from the exact focal plane of the principal focusing, a well-irradiated laser spot and great energy efficiency can be obtained.