9-MV FN Pelletron Tandem Accelerator

Our accelerator has been built by the High Voltage Engineering Corporation (HVEC) in 1973 and it was later upgraded from the original terminal voltage of 7.5 MV (FN machine) to 9 MV.

The accelerator currently delivers 28 ion species ranging from protons to gold, produced in a sputtering or duoplasmatron ion sources. A special configuration (Li charge exchange) of the duoplasmatron ion source is dedicated to 3,4He ions and an ultra-clean sputtering source.

The operating principle of this type of machine is very simple. The high voltage terminal of the accelerator is charged to maximum 9 million volts positive potential. The negative ions from the ion sources are accelerated by the positive potential on the terminal after a selection through the injection magnet (20 degrees bipolar magnet). The ions reaching the terminal region are stripped of electrons using thin foils of carbon (5-10 g/cm2). The ion beam becomes positive and is accelerated away by the same positive terminal potential. The name "Tandem" comes from this two stage acceleration process. The beam is then focused using magnetic quadrupole lenses and analyzed by A/q using a bipolar magnet. The path of the beam through the accelerator and onto the target is under vacuum (a level of 10-7 is achieved using turbo pumping).