The Nuclotron upgrade – the Nuclotron-M project, which had been started in 2007, involved the modernization of almost all of the accelerator systems, using beam time during seven runs devoted to testing newly installed equipment. Following the project goals, Xe ions were accelerated to about 1.5 GeV/u in March 2010. In December 2010, the stable and safe operation of the power supply and energy evacuation system was achieved with a field in the lattice magnets of 2 T. The successful completion of the project paves the way for further development of the Nuclotron-based Ion Collider fAcility (NICA).

The Electron String Ion Source (ESIS) developed at JINR is effectively used here during the last decade. The Tubular Electron String Ion Source (TESIS) has been put forward recently to obtain a 1-2 orders of magnitude increase in the ion output as compared with ESIS. The project is aimed at creating TESIS and studying the electron string in the tubular geometry. The new tubular source with a superconducting solenoid up to 5 T is under construction now. The method of the off axis TESIS ion extraction will be realized to get TESIS beam emittance comparable with ESIS emittance. It is expected that this new TESIS will meet all rigid conceptual and technological requirements and should provide an ion output approaching 10 mA of Ar ions in the pulsed mode and about 10 μA of Ar ions in the average current mode. Design, construction and test of separate TESIS systems are discussed in this report. TUBULAR ELECTRON STRING ION SOURCE The ESIS is based on a specially designed electron gun and an electron reflector that allows multiple uses of beam electrons [1-3]. At some conditions the electron string is formed with about few hundreds reflections for each electron. The electron string can be used for production of highly charged ions similarly to beam electrons. The interest in the ESIS mode was motivated by the attractive possibility of decreasing the electron beam power by a factor of 100 preserving simultaneously the same ion yield. The Krion-2 ESIS has been used successfully at the injection complex of JINR synchrotron Nuclotron for production of highly charged ion beams: Ar 200 A, Fe -150 A in 8 s pulses (Table 1) [3]. It was found experimentally [1-3] that the maximum number of electrons Ne accumulated in a linear string was proportional to a confined magnetic field B to the third power: Ne=κB. (1) An increase in the magnetic field from 3T in Krion-2 to 5T in constructed Krion-5T (Fig.1) permits 4.5 times increases of the ion yield. The idea of using TESIS was proposed in [4] to obtain a considerable increase of ion outputs (Table 1) in comparison with the ESIS and simultaneously a small ion beam emittance, usually provided by ESIS. Figure 1: Construction of the new JINR Krion 5T ion source at magnetic field of 5T. Table 1. Parameters of electron string ion sources Ion source Krion-2 TESIS Electron energy, keV 3÷5 3÷5 Number of stored electrons 5 10 3·10 Magnetic field, T 3 5 Ion current, mA 0.15 10 Pulse duration, s 8÷∞ 8÷∞ Maximal number of Arextracted ions 5 10 3 10 Ion extraction frequency, Hz 1 5 Average ion current, mA 0.15 10 The method of the off–axis TESIS ion extraction was proposed in [4-5] to get beam emittance comparable with ESIS one. In fact, the number of produced ions is proportional to the number of the stored electrons and for a given source length it is proportional to the beam cross-section area. The ratio of the stored electrons/ions in the tubular source NTESIS and in the solid cylindrical beam NESIS of the same length is NTESIS/NESIS≈4r/a 25÷50, where a is the radial electron beam thickness and r is the main radius for the tubular electron beam. Second crucial point is that the use of tubular geometry of drift tube structure allows avoiding the virtual cathode formation for the corresponding amount of accumulated electrons in comparison to the cylindrical drift tube structure. ___________________________________________ *Work supported by International Science and Technology Centre, grant 3454, # syresin@nusun.jinr.ru THPEC067 Proceedings of IPAC’10, Kyoto, Japan 4208 04 Hadron Accelerators T01 Proton and Ion Sources ENTS WITH QUASI-T EXPERIM UBULAR re tubular drift tube