| Paper |
Title |
Page |
| MO2002 |
Energy Doubling in a Plasma Wakefield Accelerator
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16 |
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- R. Ischebeck, M. K. Berry, I. Blumenfeld, F.-J. Decker, P. Emma, M. J. Hogan, R. H. Iverson, N. A. Kirby, P. Krejcik, R. Siemann, D. R. Walz
SLAC, Menlo Park, California
- C. E. Clayton, C. Huang, C. Joshi, W. Lu, K. A. Marsh, W. B. Mori, M. Zhou
UCLA, Los Angeles, California
- S. Deng, T. C. Katsouleas, P. Muggli, E. Oz
USC, Los Angeles, California
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In the experiment E-167 at SLAC, the compressed electron pulse from the linac traverses a lithium vapor column and creates a plasma wake, which accelerates and focuses particles in the back of the pulse. Recent experimental results show that these fields can be sustained for 85 cm, increasing the particle energy from 42 GeV to 80 GeV. Plasma electrons can be trapped in the accelerating wake, resulting in ultra-short bunches with a relatively narrow energy spread and a small divergence angle. The results agree with three-dimensional particle-in-cell simulations.
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| MOP029 |
Laser Beat-Wave Microbunching of Relativistic Electron Beam in the THz Range
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100 |
| |
- S. Tochitsky, C. Joshi, C. Pellegrini, S. Reiche, J. B. Rosenzweig, C. Sung
UCLA, Los Angeles, California
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Laser-driven plasma accelerators have recently demonstrated a ~1GeV energy gain of self-trapped electrons in a several-centimeter-long plasma channel. Potential staging of such devices will require external injection of an electron beam prebunched on the scale of 1-10 THz into a plasma accelerating structure or plasma LINAC. Seeded FEL/IFEL techniques can be used for modulation of the electron beam longitudinally on the radiation wavelength. However a seed source in this spectral range is not available. At the UCLA Neptune Laboratory a Laser Beat-Wave (LBW) microbunching experiment has begun. Interaction of the electron beam and the LBW results in ponderomotive acceleration and energy modulation on the THz scale. This stage is followed by a ballistic drift of the electrons, where the gained energy modulation transfers to the beam current modulation. Then the beam is sent into a 33-cm long undulator, where a coherent start-up of THz radiation takes place providing efficient bunching of the whole beam. The performance of LBW bunching is simulated and analyzed using 3D FEL code for the parameters of an existing photoinjector and two-wavelength TW CO2 laser system.
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| MOP026 |
Positron Source from X-rays Emitted by Plasma Betatron Motion
|
94 |
| |
- D. K. Johnson, C. E. Clayton, C. Huang, C. Joshi, W. Lu, K. A. Marsh, W. B. Mori, M. Zhou
UCLA, Los Angeles, California
- C. D. Barnes, I. Blumenfeld, F.-J. Decker, P. Emma, M. J. Hogan, R. Ischebeck, R. H. Iverson, N. A. Kirby, P. Krejcik, C. L. O'Connell, R. Siemann, D. R. Walz
SLAC, Menlo Park, California
- S. Deng, T. C. Katsouleas, P. Muggli, E. Oz
USC, Los Angeles, California
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A new method for generating positrons has been proposed that uses betatron X-rays emitted by an electron beam in a high-K plasma wiggler. The plasma wiggler is an ion column produced by the head of the beam when the peak beam density exceeds the plasma density. The radial electric field of the beam blows out the plasma electrons transversely, creating an ion column. The focusing electric field of the ion column causes the beam electrons to execute betatron oscillations about the ion column axis. At the proper plasma density, this leads to synchrotron radiation in the 1-50 MeV range. These photons strike a thin (.5Xo), high-Z target and create electron-positron pairs. A computational model was written and matched with experimental results taken at the Stanford Linear Accelerator Center. This model was then used to design a more efficient positron source, giving positron yields of 0.44 positrons/electron, a number that is close to the target goal of 1-2 positrons/electron for future positron sources.
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