Helmholtz International Center for Oliver Boine-Frankenheim GSI mbH and TU Darmstadt/TEMF FAIR accelerator theory (FAIR-AT) division Helmholtz International Center for FAIR Accelerator Theory

Helmholtz International Center for March 6, 2008Oliver Boine-Frankenheim2 Required FAIR beam intensities SIS-18 todayAfter upgrade (to SIS 100) SIS 100 Reference ionU 73+ U 28+ Maximum energy1 GeV/u 0.2 GeV/u2.7 GeV/u Maximum intensity 3x10 9 2x x x10 11 Repetition rate0.3 Hz1 Hz2.7 Hz 0.7 Hz Bunch length> 100 ns50 ns -60 ns FAIR specific beam dynamics challenges: o Intensities at the ‘space charge limit’ o High beam quality (weak or lost Landau damping) o Long accumulation time (1 s) in SIS-100 o Extreme space charge during bunch compression o … 5x10 11 U 28+ SIS 18 SIS 100 cycle

Helmholtz International Center for March 6, 2008Oliver Boine-Frankenheim3 SIS-100 dynamic aperture scan tune Beam Dynamics Computer Simulation Particle tracking in nonlinear focusing structures SIS-100 transverse apertures dynamic aperture pipe aperture lattice aperture beam HIC for FAIR: Challenges in particle tracking o Long time scales up to 10 6 turns (1 s) o ‘Thick’ medium energy beams o Nonlinear magnet errors and collective forces (Presently only a static collective space charge force can be included in long-term simulations) o Accurate beam loss predictions are required. HIC for FAIR: realistic long-term beam loss simulations for SIS-100/300 with space charge and intensity effects space charge tune spread Incoherent space charge tune shift: Dynamic aperture: Caused by the nonlinear components of the magnetic field. The boundary separating stable and chaotic particle motion.

Helmholtz International Center for March 6, 2008Oliver Boine-Frankenheim4 Loss of Landau damping below approx 10 MHz. SIS-18 transverse impedance spectrum wall (smooth) f0f0 e-cloud kicker (x) kicker (y) EM Field Simulations Ring impedances Specific impedance issues for FAIR: - Low frequencies and beam energies - Thin stainless steel beam pipe (optional corrugated) - Ferrite or magnetic alloy loaded ring components - Distributed collimation system Doliwa, Weiland (2006) Ferrite loaded kicker modules Corrugated pipe wall SIS-100/300 impedances studies to be addressed in HIC for FAIR: electron clouds, collimators, corrugated pipe -> impedance library for FAIR SIS-100 beam pipe

Helmholtz International Center for March 6, 2008Oliver Boine-Frankenheim5 Beam Dynamics Computer Simulation Particle tracking in self-consistent EM fields Specific simulation issues for FAIR: - Long time scales (up to 1 s) - Frequency range: 50 kHz-100 MHz - Impedance and space charge effects HIC for FAIR simulation studies: - Estimate instability thresholds - Estimate impedance ‘budgets’ - Verify potential cures: e.g. octupoles (increase Landau damping) 3D particle tracking (smooth focusing) example with self-consistent space charge for a long bunch in SIS-18 interacting with the kicker impedance. The large-scale simulation studies of coherent beam instabilities for FAIR are extremely demanding in terms of computer resources. In HIC for FAIR we will continue and extend these elaborate studies. Stability boundaries (from dispersion relation) Impedance (real part) Impedance (imaginary part) for dc beams V. Kornilov, et al (2008)

Helmholtz International Center for March 6, 2008Oliver Boine-Frankenheim6 Experimental verification of simulation results Observed resistive wall instability in SIS-18 growth time ≈30 ms Beam current Beam offset V.Kornilov (2006) A.Parfenova (PhD thesis, 2008) and G. Franchetti Measured beam loss vs. tune in SIS-18 HIC for FAIR: Beam dynamics experiments in SIS-18 and other high intensity hadron accelerators. o Simulation codes can only handle subsets of the long-term collective beam interactions. o Therefore an experimental verification of code predictions is absolutely necessary. o These experiments will be part of HIC for FAIR activities.

Helmholtz International Center for March 6, 2008Oliver Boine-Frankenheim7 Accelerator Theory for FAIR HIC for FAIR challenges Substantial progress has been made towards a realistic computer modeling of high intensity beams in SIS-18 and in the FAIR synchrotrons. HIC for FAIR: To address the open questions the work has to be continued and broadened. Important issues to be addressed in HIC for FAIR are: o For large-scale studies one is still forced to use reduced beam physics models (e.g. freeze space charge or neglect coherent effects). o Experimental verification of code predictions in SIS-18 or other high-current machines like the CERN PS or the BNL AGS. Important accelerator physics studies to be performed in HIC for FAIR are: o Beam loss optimization with space charge and magnet errors o Impedance contributions from beam pipes, collimators, electron clouds,.... o Intensity limits (‘impedance budgets’) from coherent instabilities o Control of coherent instabilities: enhanced Landau damping, feedback systems