Ion-cyclotron-resonance mass spectrometry with a microwave plasma source

The feasibility of coupling an electron-cyclotron-resonance (ECR) plasma-processing reactor directly to an omegatron mass spectrometer is demonstrated. The ECR plasma is created in a chamber that is coupled to the omegatron through a small, grounded orifice. Ions created in the ECR chamber flow along the magnetic field into the omegatron analysis cell, and the mass spectrum of these ions is recovered. Using this technique the mass spectra of both single-component (He) and two-component (N₂ and N) ECR plasmas were measured. The mass resolution as a function of the omegatron excitation voltage for He and N₂ plasmas was obtained and found to compare well to theoretical calculations