A simple mass spectrometer using 60 degree focusing was set up to study the (illegible) of the ions produced by various types of sources. A schematic diagram of the apparatus is shown in Fig. 1, which is to a large extent self-explanatory. The isolation transformer was simply a piece of RG (illegible) cable about three feet long and was used in order to operate the source at high accelerating voltage allowing the collector to be at essentially ground potential. The collimating slits were 0.05 (illegible) wide and were space 4 (illegible-cm?) apart. The coarse slit immediately preceding the collector cup was 0.3 (illegible) wide. The electrometer was the integrating type which indicated the potential due to the charge collected on known capacitance. The vacuum tube voltmeter indicated the potential of the 0.5 (illegible) capacitor due to the total charge reaching the slit system. It thus served as a monitor of the source output for each firing. The neon lamp was a protection for the condenser against breakdown discharges of the tube.

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