Ion optics of a single pair of $$\pm 45^{\circ}$$ angular scanning deflectors for space plasma instruments

Abstract We have conducted a parameter study on the performance of the ion optics for a $$\pm$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mo>±</mml:mo> </mml:math> 45° deflection system used in space plasma measurements. The deflection system consists of a pair of electrodes mounted on an electrostatic analyzer. Our numerical model of the ion optics demonstrates its performance, including deflection efficiency for various parameters, and investigates the empirically known upper limit of deflection efficiency. The results reveal that the deflection system essentially involves canceling the kinetic energy perpendicular to the midplane of the deflectors using the electric potential. This implies that the energy of ions capable of $$\pm$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mo>±</mml:mo> </mml:math> 45° deflection is limited to approximately twice the applied voltage. Based on the insight, an approximate analytical solution has been derived, enabling the prediction of deflection efficiency for deflector shapes represented by power functions. For future development of space plasma analyzers, deflectors can now be designed with theoretical support, similar to the electrostatic analyzers. Graphical Abstract