Electromagnetic analyzer of backscattered accelerated ions with pulse-controlled current-stabilized power supply

An electromagnetic analyzer of backscattered H+ and He+ ions featuring a sector, homogeneous magnetic field is described. The radius of the circular path of the ions to be analyzed is 340 mm, the angle of deflection is 30deg. The measured resolution of the analyzer was 0.7%, which allows analyses, using accelerated 300 keV He+ ions, of elements on the surface of solids (depth profile of implanted ions) down to a depth of 0.4 μm. The analyzer is powered from a pulse-controlled stabilized current source whose maximum output current at a voltage of 110 V is 4 A. The stabilizer is fitted with integrated circuits. In order that sufficient resolution should be achieved, the current range is divided into 8 steps. Backscattered ions within the pre-selected current step within the energy range of 70 to 300 keV are recorded using a plastic scintillation detector. The electromagnetic analyzer resolution can be improved when an electromagnet with a larger radius of the ion circular path is used. (J.B.)