PAC2013 - List of Authors (Peggs, S.)

Paper	Title	Page
WEPMA25	Harmonic Ratcheting for Fast Acceleration	1034
	N.M. Cook Stony Brook University, Stony Brook, USA J.M. Brennan, S. Peggs BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. One of the most persistent difficulties in the design of RF cavities for acceleration of charged particles is rapid and efficient acceleration over a large range of frequencies. From medical synchrotrons to accelerator driven systems, there is a need for fast acceleration of protons and light ions to hundreds of MeV. Conventionally, this is a costly undertaking, requiring specially designed ferrite loaded cavities to be tuned over a wide range of frequencies. Ferromagnetic materials allow for the precise adjustment of cavity resonant frequency, but rapid changes in the frequency and operation outside material specific frequency ranges result in significant Q-loss to the cavity. This leads to a considerable increase in power requirements. We introduce an acceleration scheme known as harmonic ratcheting which can be used to reduce the cavity frequency range when accelerating an ion beam in a synchrotron. This scheme addresses the needs of high rep. rate machines for applications such as radiation therapy in which low beam intensity is needed. We demonstrate with simulations the type of ramps achievable using this technique and consider its advantages over h=1 acceleration schemes.

Paper

Title

Page

Harmonic Ratcheting for Fast Acceleration

1034

N.M. Cook
Stony Brook University, Stony Brook, USA
J.M. Brennan, S. Peggs
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
One of the most persistent difficulties in the design of RF cavities for acceleration of charged particles is rapid and efficient acceleration over a large range of frequencies. From medical synchrotrons to accelerator driven systems, there is a need for fast acceleration of protons and light ions to hundreds of MeV. Conventionally, this is a costly undertaking, requiring specially designed ferrite loaded cavities to be tuned over a wide range of frequencies. Ferromagnetic materials allow for the precise adjustment of cavity resonant frequency, but rapid changes in the frequency and operation outside material specific frequency ranges result in significant Q-loss to the cavity. This leads to a considerable increase in power requirements. We introduce an acceleration scheme known as harmonic ratcheting which can be used to reduce the cavity frequency range when accelerating an ion beam in a synchrotron. This scheme addresses the needs of high rep. rate machines for applications such as radiation therapy in which low beam intensity is needed. We demonstrate with simulations the type of ramps achievable using this technique and consider its advantages over h=1 acceleration schemes.