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Abstract

A radio frequency excited positive ion source has been designed and constructed. Hydrogen gas is excited in a discharge tube by a radio frequency oscillator operating at a frequency of 210 mc./sec. The hydrogen is disassociated and ionized. A voltage of the order of a 2 kV is used to accelerate the positive ions through the exit canal in the end of the discharge tube. The positive ions are then accelerated and focused into a bean by two cylindrical electrostatic lenses using voltages of the order of 10 kV and 50 kV. For purposes of analysing a one lens system is used, accelerating the beam to an energy of the order of 15 kV. A magnetic analyser resolves up to mass three ions, focussing them into a Faraday cup. The source delivers a beam containing 45% protons. A total current of 800 microamperes of positive ions has been measured.