Abstract: A high pressure collision cell for use in a mass spectrometer. The high pressure collision cell has a cell length L selected to be in a range such that upon application of voltages to a pair of opposed elongate electrically conducting electrodes there is produced an electric field of sufficient strength across the collision cell length L in to aid in directing ions entering the collision cell to along a transverse flow axis. The pressure in the collision cell is maintained in a range from about 50 mTorr to 1000 mTorr and wherein the collision cell length L and the pressure are selected such that a target thickness, defined as a product of the collision cell length L and the pressure, is maintained in a range from about 0.2 to about 2 mm-Torr.