In FOTIA facility, an average vacuum of the order of 1x10~(-8) Torr is maintained for high beam transmission and minimum spread in the beam energies. The ion beams accelerated by the low energy tube are injected into the high-energy accelerating tube using the 180°-folding magnet. In order to have maximum transmission through the magnet chamber the vacuum in this section should be in the range of 10~(-8) Torr. The chamber is very narrow (14 mm x 24 mm) and offers low conductance to the vacuum system. For maintaining the required UHV inside this chamber and associated beam lines inside the high voltage terminal at 6 MV, a triode sputter-ion pump (Fig. 1) with pumping speed of 120 litres/sec is used. Triode ion pumps exhibit high pumping speeds for rare & inert gases and have very good starting characteristics.
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