A mass spectrometer includes an ion source including: an ionization chamber including an ion ejection hole, and an electron introduction port and an electron discharge port; a repeller electrode; a filament; a trap electrode; and a magnetic field forming unit. A first distance in a direction along the ion optical axis between an end of the electron introduction port on an ion ejection hole side and an inner face of a wall of the ionization chamber in which the ion ejection hole is formed and/or a second distance in a direction along the ion optical axis between an end of the electron introduction port on a repeller electrode side and the repeller electrode, is set to be larger than a radius of gyration of the thermal electron estimated based on energy imparted to the thermal electron and intensity of the magnetic field formed by the magnetic field forming unit.

A mass spectrometer includes an ion source including: an ionization chamber including an ion ejection hole, and an electron introduction port and an electron discharge port; a repeller electrode; a filament; a trap electrode; and a magnetic field forming unit. A first distance in a direction along the ion optical axis between an end of the electron introduction port on an ion ejection hole side and an inner face of a wall of the ionization chamber in which the ion ejection hole is formed and/or a second distance in a direction along the ion optical axis between an end of the electron introduction port on a repeller electrode side and the repeller electrode, is set to be larger than a radius of gyration of the thermal electron estimated based on energy imparted to the thermal electron and intensity of the magnetic field formed by the magnetic field forming unit.

A low power mass spectrometer assembly includes at least an ionization component, an electrostatic analyzer, a lens assembly, a magnet assembly and at least one detector located in a same plane as the entrance to the magnet assembly for detecting the deflected sample ions and/or fragments of sample ions, including ions or ion fragments indicative of the Vitamin D metabolite within the sample.

A low power mass spectrometer assembly includes at least an ionization component, an electrostatic analyzer, a lens assembly, a magnet assembly and at least one detector located in a same plane as the entrance to the magnet assembly for detecting the deflected sample ions and/or fragments of sample ions, including ions or ion fragments indicative of the Vitamin D metabolite within the sample.

The present disclosure discloses a method and a system for determining an energy spectrum of an incident electron beam. The method includes obtaining a plurality of deflection currents of a beam deflection device; for each of the plurality of deflection currents, determining an energy range of an ejected electron beam, and determining a target current of a target generated by the ejected electron beam irradiating the target, wherein the ejected electron beam is emitted from an output of the beam deflection device after the incident electron beam enters the beam deflection device. The method also includes determining the energy spectrum of the incident electron beam based on the energy ranges of the plurality of ejected electron beams and the corresponding target currents.

The present disclosure discloses a method and a system for determining an energy spectrum of an incident electron beam. The method includes obtaining a plurality of deflection currents of a beam deflection device; for each of the plurality of deflection currents, determining an energy range of an ejected electron beam, and determining a target current of a target generated by the ejected electron beam irradiating the target, wherein the ejected electron beam is emitted from an output of the beam deflection device after the incident electron beam enters the beam deflection device. The method also includes determining the energy spectrum of the incident electron beam based on the energy ranges of the plurality of ejected electron beams and the corresponding target currents.

A low power mass spectrometer assembly includes at least an ionization component, an electrostatic analyzer, a lens assembly, a magnet assembly and at least one detector located in a same plane as the entrance to the magnet assembly for detecting the deflected sample ions and/or fragments of sample ions, including ions or ion fragments indicative of the Vitamin D metabolite within the sample.

A low power mass spectrometer assembly includes at least an ionization component, an electrostatic analyzer, a lens assembly, a magnet assembly and at least one detector located in a same plane as the entrance to the magnet assembly for detecting the deflected sample ions and/or fragments of sample ions, including ions or ion fragments indicative of the Vitamin D metabolite within the sample.

An ion source can include a magnetic field generator configured to generate a magnetic field in a direction parallel to a direction of the electron beam and coincident with the electron beam. However, this magnetic field can also influence the path of ionized sample constituents as they pass through and exit the ion source. An ion source can include an electric field generator to compensate for this effect. As an example, the electric field generator can be configured to generate an electric field within the ion source chamber, such that an additional force is imparted on the ionized sample constituents, opposite in direction and substantially equal in magnitude to the force imparted on the ionized sample constituents by the magnetic field.

An ion source can include a magnetic field generator configured to generate a magnetic field in a direction parallel to a direction of the electron beam and coincident with the electron beam. However, this magnetic field can also influence the path of ionized sample constituents as they pass through and exit the ion source. An ion source can include an electric field generator to compensate for this effect. As an example, the electric field generator can be configured to generate an electric field within the ion source chamber, such that an additional force is imparted on the ionized sample constituents, opposite in direction and substantially equal in magnitude to the force imparted on the ionized sample constituents by the magnetic field.