An RF Linear Decelerator Mass Spectrometer

Abstract

An RF Linear Decelerator Mass Spectrometer is described, featuring resolution to mass 100.

Ions are formed by electron impact in a somewhat conventional ion chamber, utilizing an electron beam at right angles to the ion beam, temperature regulation and pressure differential for high signal to back ground ratio. All of the ions are then accelerated through 2500 volts, collimated, and then passed through a series of 24 RF gaps, spaced such that the preferred (or resonant) particles are decelerated by an amount equal to the RMS value of the RF voltage at each gap, all other particles emitting from the RF analyzer with correspondingly higher energies. The resultant “energy dispersed” beam is then separated in an electrostatic deflection system, the preferred (lowest energy) beam being collected in a Faraday bucket, and observed on a vibrating reed electrometer. A linear mass scan is achieved by varying the frequency applied to the gaps.