• S. Dobrescu, I. Branzan, C.V. Craciun, G. Dumitru, C. Florea, D. Ghita, G. Ion, G. Mihon, D. Moisa, D.V. Mosu, G. Naghel, C. Paun, S. Papureanu, T. Sava
  IFIN-HH, Magurele-Bucharest

The Bucharest FN Tan­dem Ac­cel­er­a­tor was put in op­er­a­tion in 1973 and up­grad­ed a first time in 1983 to 9 MV. In the pe­ri­od 2006-2009 a sec­ond pro­gram of the tan­dem up­grade was per­formed aim­ing to trans­form this ac­cel­er­a­tor in a mod­ern and ver­sa­tile fa­cil­i­ty for atom­ic and nu­cle­ar physics stud­ies as well as for dif­fer­ent ap­pli­ca­tions using ac­cel­er­at­ed ion beams. The up­grade was achieved by re­plac­ing the main com­po­nents of the tan­dem by new ones and by adding new com­po­nents. The old HVEC belt of the Van de Graaff gen­er­a­tor was re­placed by a "Pel­letron" sys­tem, the old in­clined field stain­less steel elec­trodes ac­cel­er­a­tor tubes were re­placed by ti­ta­ni­um spi­ral field tubes, the old HICONEX 834 sput­ter neg­a­tive ion source was re­placed by a new SNICS II sput­ter source and all old elec­tron­ic equip­ment in­clud­ing RMN and Hall probe gauss me­ters as well as low volt­age and high volt­age power sup­plies for the mag­nets, lens­es and ion sources were re­placed by new ones. The new equip­ment added to the tan­dem con­sists of a he­li­um neg­a­tive ion source, a new in­jec­tor based on a mul­ti-cath­ode ion source 40 MC-SNICS II for AMS ap­pli­ca­tions, a new GVM, a new puls­ing sys­tem in the mil­lisec­ond range and a new chop­per and bunch­ing sys­tem for puls­ing the ion beam in the nanosec­ond range. Now the tan­dem is cur­rent­ly op­er­at­ed in very sta­ble con­di­tions up to 9 MV on a basis of about 4000 hours/year ac­cel­er­at­ing a broad range of ion species.

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