Knudsen Compressors are meso/micro scale gas compressors/pumps based on thermal transpiration or thermal creep. The design of radiantly driven Knudsen Compressors is discussed, along with a model that was developed to understand their performance. Experimental pumping performances for Knudsen Compressors with one, two, five, and fifteen stage, radiantly driven cascades are also discussed. Temperature measurements across the transpiration membranes, for various pressures of Nitrogen, were obtained and compared to those predicted by the performance model. The results agree with the model to within 15% consistently under predicting the measured hot side temperature of the transpiration membrane. The pump-down curves, steady-state maximum pressure differences, and maximum flow rates produced by a single stage Knudsen Compressor were obtained. A variety of configurations were studied at pressures from 500 mTorr to atmospheric pressure. The experimental results agreed with the performance model’s predictions to within 20%.