Electron multipliers

A method for amplifying an electron signal caused by an impact of an ion with an electron emissive surface, the method comprising:

• providing an apparatus comprising:
• a first electron emissive surface configured to receive an ion and thereby emit one or more secondary electrons,
• a series of second and subsequent electron emissive surfaces configured to form an amplified electron signal from the one or more secondary electrons emitted by the first electron emissive surface, and
• one or more power supplies configured to apply bias voltage(s) to one or more of the series of second and subsequent electron emissive surfaces, the bias voltage(s) being sufficient to form the amplified electron signal,
• wherein the apparatus is configured such that in response to the ion detector receiving input ions, a terminal electron emissive surface(s) or a group of terminal electron emissive surfaces of the series of second and subsequent electron emissive surfaces are allowed to draw an electrical current at least 10-fold higher than that of a remainder of the series of second and subsequent electron emissive surface(s) so as to provide a more linear output for the ion detector as compared to the same ion detector but configured to allow for a less than 10-fold current differential,
• causing or allowing an ion to impact the first electron emissive surface, and
• applying bias voltage(s) to one or more of the emissive surfaces, the bias voltage(s) being sufficient to form the amplified electron signal.