UMD, College Park, Maryland
Beam halo is one of the major limiting factors to the effective transport of intense beams. In this paper, we use the WARP particle-in-cell code to numerically investigate the effect of different initial particle distributions on the properties of mismatch-induced halo. In particular, we use equilibrium and non-equilibrium distributions, the latter prompted by experimental measurements of the beam distribution in the University of Maryland Electron Ring (UMER). In both cases, we observe the phase space structure expected in the case of resonances between beam envelope oscillations and single-particle trajectories.
ANL, Argonne, Illinois
Fermilab, Batavia, Illinois
Superconducting (SC) technology is the only option for CW linacs and is also an attractive option for pulsed linacs. SC cavities are routinely used for proton & H-minus beam acceleration above 185 MeV. Successful development of SC cavities covering the lower velocity range (down to 0.03c) is a very strong basis for the application of SC structures in the front ends of high energy linacs. Lattice design and related high-intensity beam physics issues in a ~400 MeV linac that uses SC cavities will be presented in this talk. In particular, axially-symmetric focusing by SC solenoids provides strong control of beam space charge and a compact focusing lattice. As an example, we discuss the SC front end of the H-minus linac for the High Intesity Neutrino Source (HINS) and Project X.
IAP, Frankfurt am Main
GSI, Darmstadt
The 'Combined Zero-Degree Structure' ('Kombinierte Null Grad Struktur - KONUS') beam dynamics concept is described in detail. A KONUS period consists of a quadrupole triplet or a solenoid lens, a rebuncher section at negative synchronous phase and a multi cell zero degree synchronous particle main acceleration section. This concept is especially effective when applied for accelerator designs using H-mode resonators with ‘slim’ drift tubes which carry no focusing elements. The definition and typical ranges of KONUS lattice parameters are discussed on a general level, as well as on the basis of examples for realized or planned high current accelerators, like the GSI High Current Injector (HSI), the 70 mA, 3-70 MeV Proton Injector for the FAIR Facility and our proposal of a 125 mA D+, 5-40 MeV superconducting CH-DTL section for the International Fusion Materials Irradiation Facility (IFMIF).
LANL, Los Alamos, New Mexico
We are developing a compact deuteron-beam accelerator up to the energy of a few MeV based on room-temperature inter-digital H-mode (IH) accelerating structures with the transverse beam focusing using permanent-magnet quadrupoles (PMQ). Combining electromagnetic 3-D modeling with beam dynamics simulations and thermal-stress analysis, we show that IH-PMQ structures provide very efficient and practical accelerators for light-ion beams of considerable currents at the beam velocities around a few percent of the speed of light. IH-structures with PMQ focusing following a short RFQ can also be beneficial in the front end of ion linacs.
ORNL, Oak Ridge, Tennessee
GSI, Darmstadt
GANIL, Caen
The focus of the Working group B was to discuss the following questions:
- Summarize the state of the art in linac simulation capabilities. What are the weaknesses? What developments are needed?
- Summarize recent developments in benchmarking experimental data with simulations. What critical experiments are needed to further refine the theory and simulations?
- Summarize the present understanding and limitations of linac beam dynamics in operating linacs.
- Summarize the primary limitations to beam intensity in existing high-intensity linear accelerators.
- Summarize the key open questions in the beam dynamics of high-intensity linacs and opportunities to advance the field.