Production of He-like light and medium mass ions in laser ion source

Abstract

Operation of the laser ion source of He-like light ions designed for the first stage of the ITEP Terra Watt Accumulator ͑TWAC͒ project is discussed. A 5 J/0.5 Hz rep-rate CO 2 laser was used for generation of highly charged light ions. The absolute number of ions with different charge states for carbon and aluminum ion beams has been measured. The obtained number of C ϩ4 ions (ϳ10 11 ions/pulse) is sufficient to start the experimental proof of the accelerator scheme of the TWAC project. The investigation of shot to shot stability indicates significant increasing ͑ϳ2-3 times͒ of highly charged ion yield for the first shot onto the fresh target surface with respect to the next shots onto the same spot of aluminum target. This effect was not observed for the carbon target. Experimental results for highly charged light and medium mass ͑F, Mg, Al, Ca, Ti͒ ions produced by of 75 J single pulse CO 2 laser consisting of a master oscillator and power amplifier are also presented.

Atomic mass dependent electrostatic diagnostics of colliding laser plasma plumes

“…We note that we have previously verified that our Faraday cup design can successfully compensate for potential sources of error such as secondary electron emission, 29 which becomes problematic at energies far higher than those studied here. [30][31][32] The variation in TOF signal with laser shot number has been investigated in S p studies 28,33 previously for a small number of elements (C, Al, Ti, Fe, Ge, Nb, and Ta) for a slightly higher laser intensity (I p $ 2 Â 10 11 W cm À2 ). Although the drift tube distance was substantially greater (L > 3.5 m) than in our case, the results are broadly similar regarding the levelling off for I peak after $6 laser shots.…”

“…25 a focused beam strongly influences the expansion rate, degree of ionization, ionic yield, and recombination rates within the early phases of the rapidly expanding laser plasma plume. 28 Figure 2 shows the recorded Faraday cup TOF current trace for all elements studied in single plume (S p ) mode. Each current trace is a seven shot average.…”

“…Although there are a limited number of reports on the ionic yield from laser plasma plumes for varying atomic mass, [28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44] to our knowledge, there have been no previous reports on colliding plasma plumes studies for varying target atomic mass. To further elucidate the behaviour of laser generated colliding plasma plumes, we have utilized a Faraday cup to record the time of flight (TOF) signals from 14 different target elements ( 12 C, 27 Al, 28 Si, 48 Ti, 52 Mn, 56 Fe, 64 Cu, 91 Zr, 96 Mo, 112 Cd, 115 In, 118 Sn, 184 W, and 207 Pb) using a fixed laser fluence (F ¼ 0.25 kJ cm À2 , I p ¼ 4.2 Â 10 10 W cm À2 ) for both single and colliding plasma configurations.…”

“…To further elucidate the behaviour of laser generated colliding plasma plumes, we have utilized a Faraday cup to record the time of flight (TOF) signals from 14 different target elements ( 12 C, 27 Al, 28 Si, 48 Ti, 52 Mn, 56 Fe, 64 Cu, 91 Zr, 96 Mo, 112 Cd, 115 In, 118 Sn, 184 W, and 207 Pb) using a fixed laser fluence (F ¼ 0.25 kJ cm À2 , I p ¼ 4.2 Â 10 10 W cm À2 ) for both single and colliding plasma configurations. In this work, we investigate differences in the dynamics of both plume configurations as a function of the target's atomic mass.…”

Hyperspherical three-body model calculation for the bound 3,1S-states of Coulombic systems

“…Ancarani et al [1][2] also reported the ground and excited state energies for several three-body atomic systems obtained by applying ACCI approach. Kubicek et al [46] and Kondrashev et al [47] conducted experiments on production of He-like ions. In this paper we present energies of the low-lying bound 1,3 S-states of neutral helium and helium like two-electron Coulombic three-body systems having nuclear charge number Z in the range Z=2 -92.…”