Most modern ion mobility (IMS) and mass spectrometers operate under vacuum (≤ 10 Torr) and utilize high voltage radiofrequencies (RF) to radially confine ions. RF is widely known to be ineffective for radially confining ions at atmospheric pressure (AP) and few alternatives currently exist. To address this need, an analytical approach for radially focusing ions at AP (760 Torr) was developed and successfully simulated in SIMION 8.1. AP ion focusing was accomplished by applying nonlinear sequences of DC voltages to electrodes in a conventional stacked ring ion guide, a.k.a. drift tube (DT). This approach differs from the linear voltage sequences typically applied to DT electrodes. The voltage sequences used in our invention follow power (exponential) and quadratic series functions, though theoretically other nonlinear mathematical functions can be used. For both sequences, the voltage differences between electrodes at the beginning of the device are low and then increase to large differences between electrodes at the end of the device, according to the sequence used. Simulations show that ions initially defocus as they encounter the first few electrodes and then become intensely focused the further they travel into the device. The 'power sequence' provided the greatest amount of ion focusing, though steeper gradients (higher orders) resulted in ion losses and increased peak widths compared to a linear voltage sequence. Alternatively, the 'quadratic sequence' provided modest ion focusing but minimal to no ion losses or change in peak widths at all gradients tested. Potential energy surfaces indicate that nonlinear voltage gradients produce an electric field gradient that changes as a function of distance (spatially). This constant change establishes a pseudopotential well in space, resulting in spatial ion focusing. To the best of our knowledge, this is the first invention of an AP ion focusing device that focuses ions based on nonlinear DC voltages. The ability to focus ions at AP will improve the transmission of ions to the AP interfaces of current ion mobility and mass spectrometers and provides a fundamental basis which could lead to the development of a new AP instruments.