Identifying Multipolar Acoustic Sources by the Direct Sampling Method

This paper concerns the direct sampling method for solving the inverse problem of identifying point sources for the Helmholtz equation from far-field data. We develop some novel indicator functions which could determine the locations and intensities of the target multipolar sources with a single wavenumber. Theoretically, the indicating behaviors are rigorously analyzed. Two- and three-dimensional numerical experiments are conducted to illustrate the effectiveness and robustness of the proposed approach.