A New Ion Source.
GENERAL DYNAMICS/ASTRONAUTICS SAN DIEGO CA
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A new ion source is described where the ions are produced by bombarding a molecular beam of gas at low pressure with electrons. It is desired to produce ionizing collisions of the greatest possible number of electrons. For this purpose, each electron is propelled many times back and forth through the molecular beam, and a magnetic field is used along the electron paths to contain the electrons. In this way, a high electron density can be maintained in an almost field-free space without a flow of large currents toward the anode. Considerations of suitable dimensioning and arrangement of the electrons are presented, and the structure and preparation of the tubes used for the measurements are described in detail. Measurements with mercury ions and hydrogen ions yield currents of 1-2 mA with beam cross-sections of less than 1 sq.cm. The electron currents required for this are 1-5 mA. The electron efficiency is up to 80. Oscillograms of the two currents are plotted against the electron voltage with different magnetic fields to study the effect of the magnetic field strength and of the electron velocity. Author
- Particle Accelerators