M.V. Dubkov, V.S. Gurov, B.I. Kolotilin, M.A. Burobin

The monopole mass analyzer, as a kind of quadruple TOF mass spectrometers, is allocated a number of advantages: ease of fabrication and assembly, smaller size and weight, less stringent requirements for the parameters of the supply voltage. However, the main drawback of the monopole mass analyzer is the presence in the spectrum of «tails» of the mass peaks from the side of heavy masses, what limits the resolution, the relative sensitivity and the ability to analyze small components, this design is also complicated when assembling and adjusting. Significantly improve the analytical and mass-dimensional parameters monopole mass analyzer allows the replacement of a cylindrical rod and a V-shaped angle-electrode hyperbolic form electrodes. However, changing the profile of electrodes is not completely solves the problem of deviation from a quadratic electric potential distribution, that impairs the analytical characteristics of the device. To search for a solution to this problem, a procedure was developed, based on the calculation of potential distribution in the working volume of the analyzer by a numerical method and its approximation by a polynomial. The method of mathematical modeling investigated the effect of single components in the distribution of potential on the analytical characteristics of the monopole mass analyzer with hyperbolic electrodes. Studies have found that the presence of single components in the distribution of potential, not only does not worsen, but also leads to some improvement of analytical parameters of the mass analyzer, in particular, the dynamic range is increased up to 106, and the form of mass peak is approaching the «rectangular». These results were confirmed experimentally.