• A.A. Drozdovsky, N.N. Alexeev, S.A. Drozdovsky, A. Golubev, A.P. Kuznetsov, Yu.B. Novozhilov, S.M. Savin, B.Y. Sharkov, V.V. Yanenko
  ITEP, Moscow

Application of a plasma lens to focusing of ion beams has a number of essential advantages. It is important that the focusing capabilities of the lens depend on the stage of plasma development. Under certain conditions a magnetic field is linear, that allow to focus the beam to a very small spot. In other conditions, the magnetic field is nonlinear, that allow formation of hollow and other beam structures. Hollow cylinder-shaped beams of high energetic heavy ions are efficient drivers for implosion targets to create matter in a highly compressed state. The work deals with the study the possibility of using a plasma lens to transformation the density distribution of ions in the beam. Calculations and measurements were performed for a C⁶⁺ and Fe²⁶⁺ beams of 200 MeV/a.u.m. energy. The obtained results and analysis are reported.

• A. Sitnikov, N.N. Alexeev, A. Golubev, V.A. Koshelev, T. Kulevoy, S. Minaev, B.Y. Sharkov
  ITEP, Moscow
• D.H.H. Hoffmann, N.A. Tahir, D. Varentsov
  GSI, Darmstadt

Terra Watt Accumulator project (ITEP-TWAC) is aiming the accumulation of an ion beam accelerated up to 0.7 GeV/u in a storage ring providing intensity of heavy ions up to 10 power 12 particles per pulse for experiments on heavy ion beam-plasma interaction. For advanced experiments on high energy density physics the hollow cylindrical target is needed. A new method for RF rotation of the ion beam is applied for reliable formation of the hollow cylindrical beam. A principle of fast beam rotation by using a system of the multi-cell RF deflectors is considered in this paper. A four-cell H-mode deflecting cavity operating at the frequency of 298 MHz has been developed; similar 1.5 m long cavities being applied for both x- and y- directions. The shape of the deflecting electrodes has been optimized in order to provide the uniform deflection over the whole aperture taking into account both electric and magnetic components of the RF field. A deflecting system and a focusing quadrupole triplet applied to the beam with the energy of 450 MeV/u and normalized transverse emittance of 10*pi mrad*mm may form the quasi-hollow configuration with the inner radius up to 1.5 mm and thickness of 1 mm.