PAC2013 - List of Authors (Sahai, A. A.)

Paper	Title	Page
MOPAC10	Long Term Evolution of Plasma Wakefields	90
	A. A. Sahai, T.C. Katsouleas Duke ECE, Durham, North Carolina, USA W.B. Mori, F.S. Tsung UCLA, Los Angeles, California, USA
	Funding: NSF- PHY-0936278 We study the long-term evolution of plasma wakefields over multiple plasma-electron periods and few plasma-ion periods, much less than a recombination time. The evolution and relaxation of such a wakefield-perturbed plasma over these timescales has important implications on the upper limits of repetition-rates in plasma colliders. Intense fields in relativistic lasers (or intense beams) create highly non-linear space-charge wakefields by transferring energy to the plasma electrons. Synchronized charged-particle beams may be accelerated with acceleration/focusing gradients of tens of GeV/m. However, wakefields leave behind a plasma, not in equilibrium, with a relaxation time of multiple plasma-electron periods. Ion motion, over ion timescales, caused by energy transfer from the driven plasma-electrons to the plasma-ions can create interesting plasma states. Eventually, during this long-term evolution the dynamics of plasma de-coheres, thermalizing into random motion (2nd law of thermodynamics), dissipating energy away from the wakefields. Wakefield-drivers interacting with such a relativistically hot-plasma lead to plasma wakefields that differ from the wakefields in a cold-plasma. * J. Marques et al., Phys. Rev. Lett. 76 (1996) 10.1103/PhysRevLett.76.3566 L. Gorbunov et al., Phys. Plasma 10 (2003) 10.1063/1.1559011 A. Maksimchuk et al., Phys. Plasma 15 (2008) 10.1063/1.2856373

MOPAC30	Multibunch Beam Physics at FACET	132
	S.J. Gessner, E. Adli, K.L.F. Bane, F.-J. Decker, Z.D. Farkas, R.K. Jobe, M.D. Litos, M.C. Ross SLAC, Menlo Park, California, USA T.C. Katsouleas, A. A. Sahai Duke ECE, Durham, North Carolina, USA
	Funding: Work supported [optional: in part] by the U.S. Department of Energy under contract number DE AC0276SF00515. Plasma wakefield studies are normally conducted as single-shot experiments. Here, single-shot means that the plasma returns to its original state before the next bunch passes through the plasma. The time scale for the plasma to return to equilibrium is 10-100 ns, which is comparable to the bunch separation in proposed linear colliders. The SLAC linac typically delivers beam at a rate of 10 Hz to FACET but can be operated in a manner that delivers two electron bunches per RF pulse. We explore operation modes with beam separations as small 5.6 ns so that high repetition rate plasma wakefield acceleration can be studied at FACET.

Paper

Title

Page

Long Term Evolution of Plasma Wakefields

90

A. A. Sahai, T.C. Katsouleas
Duke ECE, Durham, North Carolina, USA
W.B. Mori, F.S. Tsung
UCLA, Los Angeles, California, USA

Funding: NSF- PHY-0936278
We study the long-term evolution of plasma wakefields over multiple plasma-electron periods and few plasma-ion periods, much less than a recombination time. The evolution and relaxation of such a wakefield-perturbed plasma over these timescales has important implications on the upper limits of repetition-rates in plasma colliders. Intense fields in relativistic lasers (or intense beams) create highly non-linear space-charge wakefields by transferring energy to the plasma electrons. Synchronized charged-particle beams may be accelerated with acceleration/focusing gradients of tens of GeV/m. However, wakefields leave behind a plasma, not in equilibrium, with a relaxation time of multiple plasma-electron periods. Ion motion, over ion timescales, caused by energy transfer from the driven plasma-electrons to the plasma-ions can create interesting plasma states. Eventually, during this long-term evolution the dynamics of plasma de-coheres, thermalizing into random motion (2nd law of thermodynamics), dissipating energy away from the wakefields. Wakefield-drivers interacting with such a relativistically hot-plasma lead to plasma wakefields that differ from the wakefields in a cold-plasma.
* J. Marques et al., Phys. Rev. Lett. 76 (1996) 10.1103/PhysRevLett.76.3566
** L. Gorbunov et al., Phys. Plasma 10 (2003) 10.1063/1.1559011** A. Maksimchuk et al., Phys. Plasma 15 (2008) 10.1063/1.2856373

MOPAC30

Multibunch Beam Physics at FACET

132

S.J. Gessner, E. Adli, K.L.F. Bane, F.-J. Decker, Z.D. Farkas, R.K. Jobe, M.D. Litos, M.C. Ross
SLAC, Menlo Park, California, USA
T.C. Katsouleas, A. A. Sahai
Duke ECE, Durham, North Carolina, USA

Funding: Work supported [optional: in part] by the U.S. Department of Energy under contract number DE AC0276SF00515.
Plasma wakefield studies are normally conducted as single-shot experiments. Here, single-shot means that the plasma returns to its original state before the next bunch passes through the plasma. The time scale for the plasma to return to equilibrium is 10-100 ns, which is comparable to the bunch separation in proposed linear colliders. The SLAC linac typically delivers beam at a rate of 10 Hz to FACET but can be operated in a manner that delivers two electron bunches per RF pulse. We explore operation modes with beam separations as small 5.6 ns so that high repetition rate plasma wakefield acceleration can be studied at FACET.