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TY - CONF AU - Muggli, P. AU - Adli, E. AU - Amorim, L.D. AU - Gessner, S.J. AU - Hogan, M.J. AU - Joshi, C. AU - Li, S.Z. AU - Litos, M.D. AU - Lopes, N.C. AU - Marsh, K.A. AU - Mori, W.B. AU - Olsen, V.K.B. AU - Reimann, O. AU - Vafaei-Najafabadi, N. AU - Vieira, J. ED - Petit-Jean-Genaz, Christine ED - Arduini, Gianluigi ED - Michel, Peter ED - Schaa, Volker RW TI - Electron Bunch Self-modulation in Long Plasmas at SLAC FACET J2 - Proc. of IPAC2014, Dresden, Germany, June 15-20, 2014 C1 - Dresden, Germany T2 - International Particle Accelerator Conference T3 - 5 LA - english AB - We study the physics of self-modulation instability (SMI) of long, when compared to the wake wavelength, electron and positron bunches in pre-formed plasmas at SLAC-FACET. Self-modulation is the result of the action of focusing/defocusing transverse wakefields on the bunch radius. Self-modulation leads to observables such as overall defocusing of the bunch, periodic modulation of the bunch radius at the wake period and multi-GeV energy gain/loss by drive bunch particles. Defocusing is observed from OTR images, radial self-modulation from CTR spectra and interferometric traces and energy gain/loss from energy spectra with sub-GeV resolution. The plasma density is varied by changing the vapor density ionized by a laser/axicon system. The bunch length, radius and charge can also be varied. The SMI can be seeded using a notch collimator system. Numerical simulations indicate that seeding the SMI mitigates the hose instability. Hose instability can also be seeded, for example by using the RF deflecting cavity to impart a tilt to the incoming bunch axis. The overall experimental plan as well as the latest experimental results obtained with electron bunches will be presented. PB - JACoW CP - Geneva, Switzerland SP - 1476 EP - 1478 KW - plasma KW - wakefield KW - experiment KW - electron KW - radiation DA - 2014/07 PY - 2014 SN - 978-3-95450-132-8 DO - 10.18429/JACoW-IPAC2014-TUPME050 UR - http://jacow.org/ipac2014/papers/tupme050.pdf ER -