GSI, Darmstadt
Resonant effects caused by space charge may occur in circular as well as linear accelerators for high intensity. In the present work we focus on the so-called space charge structure resonances in 2D approximation, where the driving force is induced by space charge only (emittance exchange, fourth and sixth order structure resonances) and show that they can be described by a common class of scaling laws. A distinctive feature is the presence or absence of trapping of particles, which is also reflected in the power of the scaling law. An important requirement is the fully self-consistent modeling, which describes correctly the evolution of beam core as well as halo.
GSI, Darmstadt
In the talk we report on an extensive experimental campaign performed at GSI on the SIS18 synchrotron. We measured the evolution of beam properties over 1 second storage of several beams for several working points in the vicinity of a machine resonance. With this data we benchmark our code predictions and test the understanding of the underlying beam degradation mechanisms.
GSI, Darmstadt
ORNL, Oak Ridge, Tennessee
CEA, Gif-sur-Yvette
Systematic measurements on transverse rms-emittance growth along the Alvarez DTL of the GSI UNILAC were performed. A high intensity argon beam was used to measure rms-growth for different transverse phase advances along the DTL. The transverse tune depression varied from 21% to 43%. For benchmarking of the experimental results four different beam dynamics codes were used: DYNAMION, PARMILA, PARTRAN, and LORASR. This paper is on the results of the experiments, the reconstruction of the initial conditions for the simulations, and on the agreement between simulations and experiments. Additionally, successful suppression of rms-growth by systematic matching is reported.
ORNL, Oak Ridge, Tennessee
GSI, Darmstadt
The 4ν=1 resonance of a linac is found when the depressed tune is around 90 deg. It is observed that this fourth order resonance is dominating over the better known envelope instability and practically replacing it. Simulation study shows a clear emittance growth by this resonance and its stopband. Experimental measurement of the stopband of this resonance is proposed and conducted in 2008 using the UNILAC at GSI. This study will serve as an excellent benchmarking.
SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy.
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.