This document discusses improving the performance of miniature mass spectrometers through the use of a high-efficiency cross-beam magnetic electron-impact (CBM-EI) ion source. 3D simulations show the CBM-EI concentrates and amplifies the ion beam. Experimental results indicate the CBM-EI improves sensitivity for low mass ions like protons compared to conventional EI sources. However, thermal ions below about 14 amu still experience magnetic deflection that reduces transmission efficiency, particularly for protons. Further optimization of the CBM-EI design is needed to minimize this effect for hydrogen applications.