Transition between Instability and Seeded Self-Modulation of a Relativistic Particle Bunch in Plasma
Fabian Batsch, P. Muggli, R. Agnello, C. Ahdida, M. C. Amoedo Goncalves, Y. Andrèbe, Ö. Apsimon, R. Apsimon, A.-M. Bachmann, M. A. Baistrukov, P. Blanchard, F. Braunmüller, Philip Burrows, B. Buttenschön, A. Caldwell, J. Chappell, E. Chevallay, М. Chung, D. Cooke, Heiko Damerau, C. Davut, G. Demeter, H. Lars Deubner, S. Doebert, John Farmer, A. Fasoli, V. N. Fedosseev, R. Fiorito, Ricardo Fonseca, F. Friebel, I. Furno, Luca Garolfi, Spencer Gessner, Ishkhan Gorgisyan, A. A. Gorn, E. Granados, M. Granetzny, Tim Graubner, O. Grulke, Y. Kadi, Vasyl Hafych, Anton Helm, James R. Henderson, M. Hüther, I. Yu. Kargapolov, S. Kim, Florian Kraus, M. Krupa, T. Lefèvre, Linbo Liang, S. Liu, N. Lopes, К. В. Лотов, Mikhail Martyanov, S. Mazzoni, D. Medina Godoy, V. A. Minakov, J. T. Moody, K. Moon, P. I. Morales Guzmán, M. Moreira, Tatiana Nechaeva, E. Nowak, C. Pakuza, H. Panuganti, A. Pardons, A. Perera, J. Pucek, A. Pukhov, Rebecca Ramjiawan, S. Rey, K. Rieger, O. Schmitz, E. Senes, L. O. Silva, R. Speroni, Р. И. Спицын, C. Stollberg, A. Sublet, A. Topaloudis, N. Torrado, П. В. Туев, M. Turner, Francesco Velotti, L. Verra, V. Verzilov, J. Vieira, Helmut Vincke, Carsten Welsch, M. Wendt, M. Wing, Peerawan Wiwattananon, Joseph Wolfenden, Benjamin Woolley, Guoxing Xia, M. Zepp, G. Zevi Della Porta
Abstract
We use a relativistic ionization front to provide various initial transverse wakefield amplitudes for the self-modulation of a long proton bunch in plasma. We show experimentally that, with sufficient initial amplitude [≥(4.1±0.4) MV/m], the phase of the modulation along the bunch is reproducible from event to event, with 3%-7% (of 2π) rms variations all along the bunch. The phase is not reproducible for lower initial amplitudes. We observe the transition between these two regimes. Phase reproducibility is essential for deterministic external injection of particles to be accelerated.