15 documents found, page 1 of 2
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...
Filamentation of a relativistic proton bunch in plasma
Verra, L.; Amoedo, C.; Torrado, N.; Clairembaud, A.; Mezger, J.; Pannell, F.; Pucek, J.; van Gils, N.; Bergamaschi, M.; Della Porta, G. Z.; Lopes, N.We show in experiments that a long, underdense, relativistic proton bunch propagating in plasma undergoes the oblique instability, which we observe as filamentation. We determine a threshold value for the ratio between the bunch transverse size and plasma skin depth for the instability to occur. At the threshold, the outcome of the experiment alternates between filamentation and self-modulation instability (evi...
Simulation and experimental study of proton bunch self-modulation in plasma wit...
Morales Guzmán, P. I.; Muggli, P.; Agnello, R.; Ahdida, C. C.; Aladi, M.; Amoedo Goncalves, M. C.; Andrebe, Y.; Apsimon, O.; Apsimon, R.We present numerical simulations and experimental results of the self-modulation of a long proton bunch in a plasma with linear density gradients along the beam path. Simulation results agree with the experimental results reported [F. Braunmller, T. Nechaeva et al. (AWAKE Collaboration), Phys. Rev. Lett. 125, 264801 (2020)PRLTAO0031-900710.1103/PhysRevLett.125.264801]: with negative gradients, the charge of the...
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...
Cognitive appraisal in fish: stressor predictability modulates the physiologica...
Cerqueira, M.; Millot, S.; Felix, A.; Silva, T.; Oliveira, G. A.; Oliveira, C. C. V.; Rey, S.; MacKenzie, S.; Oliveira, Rui FilipeThe role of cognitive factors in triggering the stress response is well established in humans and mammals (aka cognitive appraisal theory) but very seldom studied in other vertebrate taxa. Predictability is a key factor of the cognitive evaluation of stimuli. In this study, we tested the effects of stressor predictability on behavioral, physiological and neuromolecular responses in the European sea bass (Dicent...
Cognitive appraisal in fish: stressor predictability modulates the physiologica...
Cerqueira, Marco; Millot, S.; Felix, A.; Silva, T.; Oliveira, G. A.; Oliveira, Catarina; Rey, S.; MacKenzie, S.; Oliveira, R.The role of cognitive factors in triggering the stress response is well established in humans and mammals (aka cognitive appraisal theory) but very seldom studied in other vertebrate taxa. Predictability is a key factor of the cognitive evaluation of stimuli. In this study, we tested the effects of stressor predictability on behavioral, physiological and neuromolecular responses in the European sea bass (Dicent...
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...