Tech-X, Boulder, Colorado
KEK, Ibaraki
BNL, Upton, Long Island, New York
Funding: Supported in part by the DOE Office of Science, Office of Nuclear Physics under grant No. DE-FG02-06ER84508.
Non-scaling FFAGs are sensitive to a slew of resonances during the acceleration ramp. An important consideration - because it affects the amount of rf power required - will be the speed at which resonances must be crossed. We present simulations of possible non-scaling FFAGs, focusing especially on the effects of space charge, using newly developed capabilities in the code PTC*.
* E. Forest, Y. Nogiwa, F. Schmidt, "The FPP and PTC Libraries", ICAP'2006.
Tech-X, Boulder, Colorado
Funding: Supported by the US DOE Office of Science, Office of Nuclear Physics under grant DE-FG02-06ER84508.
The design of an accelerator with a large energy acceptance requires careful consideration of fringe-field effects*. This applies particularly to the design of fixed-field alternating gradient (FFAG) accelerators. We consider magnets in straight and curved geometries, and with multipole or mid-plane symmetries. The longitudinal magnet profiles we consider include a simple hyperbolic tangent and a more realistic six-parameter Enge function. We show that when the fields are modeled using power series expansions in a transverse parameter, the domain of convergence is determined by the fringe-field decay length. We also demonstrate the use of these models in the tracking code PTC**.
*M. Berz, B. Erdelyi, and K. Makino, "Fringe field effects in small rings of large acceptance", PRSTAB 3, 124001, 2000
**E. Forest, Y. Nogiwa, F. Schmidt, "The FPP and PTC Libraries",ICAP'2006
Tech-X, Boulder, Colorado
Funding: Supported in part by the DOE Office of Science, Office of High-Energy Physics under grant No. DE-FG02-06ER84485.
We present realistic models, including fringes, for several standing-wave modes in rf cavities. These models include a simple accelerating mode and a TM-110 (crab) mode. They are useful for the accurate computation of transfer maps* as well as for constructing model fields that can be used for testing and comparing a variety of rf cavity codes.
*D.T. Abell, "Numerical computation of high-order transfer maps for rf cavities", Phys. Rev. ST Accel. Beams 9, 052001, (2006).
Tech-X, Boulder, Colorado
KEK, Ibaraki
BNL, Upton, Long Island, New York
Funding: Supported in part by the DOE Office of Science, Office of Nuclear Physics under grant No. DE-FG02-06ER84508.
Recent simulations of non-scaling FFAGs suggest that the effects of magnet fringe fields are of signal importance. We present PTC* simulations that include realistic models for the fringes. In particular, we study how fringe extent and other parameters affect important measures of machine performance.
*E. Forest, Y. Nogiwa, F. Schmidt, "The FPP and PTC Libraries", ICAP'2006.
Tech-X, Boulder, Colorado
Funding: Supported in part by the DOE Office of Science, Office of High-Energy Physics under grant No. DE-FG02-06ER84485.
We present our recently developed capability for generating High-Order Mode (HOM) maps of rf cavity fields for use in particle tracking code-based simulations. We use VORPAL field data as a starting point, and follow the approach of* to produce the maps that are subsequently incorporated into the MaryLie/IMPACT and Synergia frameworks. We present and discuss the results of applying this new modeling tool to crab cavity simulations.
*D.T. Abell, "Numerical computation of high-order transfer maps for rf cavities", Phys. Rev. ST Accel. Beams 9, 052001, (2006).