Heavy ion hollow beam formation at the energy of 1 AGeV for implosion experiments using an original RF system for fast rotation

Abstract For experiments at Facility for Antiprotons and Ion Research (FAIR) on high energy density states in matter produced by heavy ion beams, a hollow cylindrical target combined with cylindrical geometry of the ion beam energy deposition region is required. This combination facilitates extremely high densities and pressures on the axis of the imploding cylinder if a hollow or multi-layered target is imploded using a hollow beam with an annular focal spot. We report investigations on a new method for radio frequency rotation of the ion beam, which is proposed for the Laboratory Planetary Sciences (LAPLAS) experiment in order to produce reliably such a hollow beam of ∼2 mm in diameter. For this purpose the beam delivered from the synchrotron (SIS-100) will be transformed by means of fast rotation around a cylindrical axis. The specified RF system consisting of two deflecting cavities is currently under development. An operating rotation frequency of 325 MHz has been chosen. According to simulations and analytical models, this frequency is sufficient for uniform target illumination at the power deposition level of about 10 TW/g. The RF rotation system will be placed in the beam transport line at a distance from the target, which is equal to one quarter wavelength of the transverse beam oscillations. The design of the rotation system and layout of the target–rotation system and focusing elements are presented.