Electromagnetic direct and inverse problems for a surface-breaking crack in a conductor at a high frequency

The electromagnetic direct and inverse problems for a surface-breaking crac k in a conductor are considered at a high frequency. The direct problem, wh ich is transferred to a two-dimensional potential problem in the unfolded c onfiguration, is solved by a boundary integral equation method. The boundar y integral equation (a well-posed Fredholm integral equation of the second kind) for the normal derivative of the potential on the interior boundary o f the crack is derived. The potential distribution at the open mouth of the crack is used to determine the shape of the crack. The inverse problem is solved by a genetic algorithm combined with a conjugate gradient method. (C ) 1999 American Institute of Physics. [S0021-8979(99)01819-8].