Patent ID: 8334506
Filing Date: 2012-12-18
Classification: H01J

Abstract:
1. An ion trap mass spectrometer comprising: a conductive ring-shaped central electrode having a first aperture extending, from a first open end to a second open end; a signal source generator configured to generate a trap signal having at least an alternating current (AC) component between a first and second terminal, wherein the first terminal is coupled to the central electrode and the second terminal is coupled to a reference voltage potential; a conductive first undivided electrode end cap disposed adjacent to the first open end of the central electrode and coupled to a first DC reference voltage potential, wherein a first intrinsic capacitance is formed between a surface of the first undivided electrode end cap and a surface of the first open end of the central electrode; and a conductive second undivided electrode end cap disposed adjacent to the second open end of the central electrode and coupled to a second DC reference voltage potential with a first electrical circuit, wherein a second intrinsic capacitance is formed between a surface of the second undivided electrode end cap and a surface of the second open end of the central electrode, wherein a fractional part of the trap signal is impressed on the second undivided electrode end cap in response to a voltage division of the trap signal by the second intrinsic capacitance and an impedance of the first electrical circuit; and wherein the central electrode, the first undivided electrode end cap, and the second undivided electrode end cap together form a cylindrical ion trap; and wherein the first electrical circuit comprises a resistor having, an impedance in the range of 1 MΩ to 10 MΩ.