7 documents found, page 1 of 1
Experimental observation of the motion of ions in a resonantly driven plasma wa...
Turner, M.; Walter, E.; Amoedo, C.; Torrado, N.; Lopes, N.; Sublet, A.; Bergamaschi, M.; Pucek, J.; Mezger, J.; van Gils, N.; Verra, L.We show experimentally that an effect of motion of ions, observed in a plasma-based accelerator, depends inversely on the plasma ion mass. The effect appears within a single wakefield event and manifests itself as a bunch tail, occurring only when sufficient motion of ions suppresses wakefields. Wakefields are driven resonantly by multiple bunches, and simulation results indicate that the ponderomotive force ca...
Transition between instability and seeded self-modulation of a relativistic par...
Batsch, F.; Muggli, P.; Agnello, R.; Ahdida, C. C.; Amoedo Goncalves, M. C.; Andrebe, Y.; Apsimon, O.; Apsimon, R.; Bachmann, A.-M.; Baistrukov, M. A.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 2?) rms variations all along the bunch. The phase is not reproducible for lower ...
Analysis of proton bunch parameters in the AWAKE experiment
Hafych, V.; Caldwell, A.; Agnello, R.; Ahdida, C. C.; Aladi, M.; Amoedo Goncalves, M. C.; Andrebe, Y.; Apsimon, O.; Apsimon, R.; Bachmann, A.-M.A precise characterization of the incoming proton bunch parameters is required to accurately simulate the self-modulation process in the Advanced Wakefield Experiment (AWAKE). This paper presents an analysis of the parameters of the incoming proton bunches used in the later stages of the AWAKE Run 1 data-taking period. The transverse structure of the bunch is observed at multiple positions along the beamline us...
Experimental study of extended timescale dynamics of a plasma wakefield driven ...
Chappell, J.; Adli, E.; Agnello, R.; Aladi, M.; Andrebe, Y; Apsimon, O.; Apsimon, R.; Bachmann, A.-M.; Baistrukov, M. A.; Batsch, F.; Bergamaschi, M.Plasma wakefield dynamics over timescales up to 800 ps, approximately 100 plasma periods, are studied experimentally at the Advanced Wakefield Experiment (AWAKE). The development of the longitudinal wakefield amplitude driven by a self-modulated proton bunch is measured using the external injection of witness electrons that sample the fields. In simulation, resonant excitation of the wakefield causes plasma ele...
Proton bunch self-modulation in plasma with density gradient
Braunmuller, F.; Nechaeva, T.; Adli, E.; Agnello, R.; Aladi, M.; Andrebe, Y.; Apsimon, O.; Apsimon, R.; Bachmann, A. -M.; Baistrukov, M. A.; Batsch, F.We study experimentally the effect of linear plasma density gradients on the self-modulation of a 400 GeV proton bunch. Results show that a positive or negative gradient increases or decreases the number of microbunches and the relative charge per microbunch observed after 10 m of plasma. The measured modulation frequency also increases or decreases. With the largest positive gradient we observe two frequencies...
Proton beam defocusing in AWAKE: comparison of simulations and measurements
Gorn, A.; Turner, M.; Adli, E; Agnello, R.; Aladi, M.; Andrebe, Y.; Apsimon, O.; Apsimon, R.; Bachmann, A. -M.; Baistrukov, M. A.; Batsch, F.In 2017, AWAKE demonstrated the seeded self-modulation (SSM) of a 400 GeV proton beam from the Super Proton Synchrotron at CERN. The angular distribution of the protons deflected due to SSM is a quantitative measure of the process, which agrees with simulations by the two-dimensional (axisymmetric) particle-in-cell code LCODE to about 5%. The agreement is achieved in beam population scans at two selected plasma...
Experimental study of wakefields driven by a self-modulating proton bunch in pl...
Turner, M.; Muggli, P.; Adli, E.; Agnello, R.; Aladi, M.; Andrebe, Y.; Apsimon, O.; Apsimon, R.; Bachmann, A.-M.; Baistrukov, M. A.; Batsch, F.We study experimentally the longitudinal and transverse wakefields driven by a highly relativistic proton bunch during self-modulation in plasma. We show that the wakefields’ growth and amplitude increase with increasing seed amplitude as well as with the proton bunch charge in the plasma. We study transverse wakefields using the maximum radius of the proton bunch distribution measured on a screen downstream fr...