3 MV Pelletron Accelerator.
A 3MV Pelletron accelerator system has been added in 2014, to serve our users for high energy ion beam irradiation experiments. The complete system, which is 15.7 m long, has three major sections: (1) the ion sources, (2) the actual ion beam accelerator (made by NEC, http://www.pelletron.com/) including the quadrupole focusing unit the high energy magnet that could deliver beams to 5 separate beamlines and, (3) the beamlines (to date two lines have been built and two more are in the queue). The instrument is capable of delivering a focused beam with 3 mm FWHM; this beam could be raster-scanned, over a max area of 10 mm(V) by 17 mm (H). The ion beam can also be defocussed to cover a uniform area of about around 5mm/5 mm. This Pelletron accelerator is capable of accelerating a variety of ion species and multiple ion states. The principle of operation of this type of accelerator is simple. Negative ion beams are injected into the accelerator low energy tube; once inside the terminal (the portion between the low energy and high energy tubes), the negative ions enter an area rich in nitrogen where the extra electron plus one or more electrons are stripped off generating positive ions; these ions are accelerated through the second tube to be delivered at the exit of the accelerator. The maximum terminal voltage is 3MV.
Specifications of the Pelletron:
- Peabody brand PS120 external Cs sputter source capable of delivering more than 500 nA of Fe++ ions. The maximum energy achieved for Fe+++ is 9 MeV and a range of ions in stainless steels of about 2 micrometers.
- Torvis ion source (NEC) capable of delivering up to 100 uA at the low energy end and with currents of about 25-30 microamperes on targets (40 uA total).
- Alphatross ion source (NEC) for production of He currents at or above 50 nA levels ontargets for surface analysis.
Target chamber vacuum: 10 -8 Torr range or better
Sample temperature control: LN, RT to 600°C