We present a detailed description of the characteristics of a ratchet-type small-scale gas-pump suggested by Donkov et al. [1]. The pump consists of a ratchet channel with the temperature gradient applied between the opposing walls, see Fig. 1-a. Here, we report the physical mechanism of flow induction within the pump and show that the combination of reflection properties, geometric configuration and boundary temperature of this pump induces a directed radiometric-type flow (Fig. 1-b). Benefiting from DSMC simulations, we suggest the optimum working condition and geometry of the pump. An illustrative example of the velocity contour in the pump is shown in Fig. 1-c. Comparison of DSMC simulation with analytical relations is reported, where appropriate, see Fig. 1-d.

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