Abstracts Brochure - CERN

WEOAPA01
WEOAPA02
28-Jun-06 14:00 - 15:00 WEOAPA — Linear Colliders, Lepton Accelerators . . .
WEOAPA — Linear Colliders, Lepton Accelerators and
New Acceleration Techniques
Demonstration of Energy Gain Larger than 10GeV in a Plasma Wakefield Accelerator
P. Muggli, S. Deng, T.C. Katsouleas, E. Oz (USC) D. Auerbach,
C.E. Clayton, C. Huang, D.K. Johnson, C. Joshi, W. Lu, K.A. Marsh,
W.B. Mori, M. Zhou (UCLA) I. Blumenfeld, F.-J. Decker, P. Emma,
M.J. Hogan, R. Ischebeck, R.H. Iverson, N.A. Kirby, P. Krejcik, R.
Siemann, D.R. Walz (SLAC)
We have recently demonstrating the excitation
of accelerating gradients as large as 30
GV/m* using the ultra-short, 28.5 GeV electron
bunches now available at the Stanford
Linear Accelerator Center. As a result, the
electrons in the back of the bunch gained
about 3 GeV over the 10 cm-long plasma with
a density of ?2.5x1017 e /cm-3. In recent experiments, energy gains in excess of 10 GeV, by far the largest in any
plasma accelerators, have been measured over a plasma length of ?30 cm. Moreover, systematic measurements show
the scaling of the energy gain with plasma length and density, and show the reproduceability and the stability of
the acceleration process. These are key steps toward the application of beam-driven plasma accelerators or plasma
wakefield accelerators (PWFA) to doubling the enregy of a future linear collider without doubling its length. We are
preparing for experiments to be performed in February-March 2006 aiming at doubling the energy of the 28.5 GeV
beam over a plasma length of less than one meter, a distance two thousand times shorter than the accelerator that
created the incoming beam. The latest experimental results will be presented.
*M. J. Hogan et al. Phys. Rev. Lett. 95, 054802, 2005.
Optimum Frequency and Gradient for the CLIC Main Linac Accelerating Structure
A novel procedure for the optimization of the
A. Grudiev, D. Schulte, W. Wuensch (CERN)
operating frequency, the accelerating gradient,
and many other parameters of the CLIC
main linac is presented. Based on the new accelerating structure design HDS (Hybrid Damped Structure), the optimization
procedure takes into account both beam dynamics (BD) and RF constraints. BD constraints are related to
emittance growth due to short- and long-range transverse wakefields. RF constraints are related to RF breakdown and
pulsed surface heating limitations of the accelerating structure. Interpolation of beam and structure parameters in a
wide range allows hundreds of millions of structures to be analyzed. Only those structures which satisfy BD and RF
constraints are evaluated further in terms of ratio of luminosity to main linac input power, which is used as the figure
of merit. The frequency and gradient have been varied in the range 12-30 GHz and 90-150 MV/m, respectively. It is
shown that the optimum frequency varies in the range from 16 to 20 GHz depending on the accelerating gradient and
that the optimum gradient is below 100 MV/m and that changing frequency and gradient can double the luminosity
for the same main linac input power.
266 Chair: P. Burrows (Queen Mary University of London, London)