BEM SHAPE OPTIMIZATION TECHNIQUE APPLIED TO CRYOSURGICAL PROBE TIP DESIGN

Abstract

This paper describes an iterative numerical optimization procedure for generating the cryosurgical probe tip geometry to produce the desired lethal temperature envelope for steady-state axisymmetric systems. The Kirchhoff transformation is used to include the nonlinear effect of variable thermal conductivity at cryogenic temperatures. The boundary-element method (BEM) is used to solve the governing differential equation at each step in the iteration. The shape optimization procedure involves sequential searches of radial vectors to determine the optimum location for each node at each step in the iteration. Experimental data are obtained for three probe tip geometries, and the experimental data compare favorably with the results of the numerical solution.