A radial fin cryogenic pumping array design is described which enhances the pumping efficiency of high enthalpy and high kinetic energy flows in vacuum. In general, these flows have relatively low sticking coefficients due to the large temperature differences between the particles in the flow and the cryogenic pumping surfaces. A Monte Carlo numerical model has been developed to investigate the pumping efficiency of the radial fin array. A comparison of the pumping efficiency of the radial fin array with a flat plate pumping surface has shown that particles with a high sticking coefficient will be pumped better with a simple flat panel, whereas particles with low sticking coefficients will be more efficiently pumped with the radial fin array. A set of experiments has been performed to investigate the pumping efficiency of the radial fin array as manufactured. These experiments compared the radial fin results to a more traditional flat plate pumping surface with a neutral gas flow. The experimental results indicate that there are flow regimes in which the radial fins are more efficient at pumping incident particles than a flat surface. (C) 2010 American Vacuum Society. [DOI: 10.1116/1.3497029]