BEGIN:VCALENDAR VERSION:2.0 PRODID:-//CERN//INDICO//EN BEGIN:VEVENT SUMMARY:Modern trends in plasma wakefield acceleration DTSTART;VALUE=DATE-TIME:20260923T150000Z DTEND;VALUE=DATE-TIME:20260923T152000Z DTSTAMP;VALUE=DATE-TIME:20260914T050901Z UID:indico-contribution-562@indico.bitp.kiev.ua DESCRIPTION:Speakers: Vasyl Maslov ()\nHigh-efficiency acceleration of cha rged particle beams in the plasma wakefield accelerator was studied experi mentally and by numerical simulation. The most impressive experimental res ults [1] until now in electron accelerating by a wakefield\, excited in a plasma\, have been achieved using capillary-generated plasma. Plasma-wakef ield acceleration provides high accelerating gradients [1\,2]\, promises c ompact accelerators of high-brightness and high-energy electron beams. App lications of plasma-wakefield accelerators\, in particular\, particle coll iders and free-electron lasers demand low energy spread beams\, their smal l emittance\, high current of accelerated bunches\, large transformer rati o and high-efficiency operation. Achievement of these requires plateau for mation on both the accelerating field for witness-bunch and the decelerati ng fields for driver-bunch. As it is known plateau formation is possible b y controlled beam loading with careful shaping current profile and beam ch arge selection. We will demonstrate by numerical simulation by PIC code an d analytically such optimal beam loading in plasma wakefield accelerators. Problems of acceleration of positron bunches in plasma\, focusing and sta ble transport of electron and positron bunches in plasma are important. In the blowout regime the hose instability can appear. Earlier investigation s [3\,4] show that the instability is essentially suppressed if the focusi ng force is inhomogeneous along the bubble\, and radial inhomogeneity can be additional effect. The problem of the instability can be solved in weak ly nonlinear regime. In weakly nonlinear regime throughout the areas of th e driver and witness bunches the focusing force is inhomogeneous. Radial i nhomogeneity of residual plasma electron distribution also leads to bunch stabilization. We will present results of analytical investigation of hose instability suppression in plasma wakefield accelerator driven by electro n bunch in the weakly nonlinear and blowout regimes. \nThe resonant sequen ce of electron bunches can be unstable due to the destruction of the bunch es. In this report we show by numerical simulation and analytically the po ssible way of suppressing this instability by shaping of the bunches. \nWe will present in the paper results on: \n- wakefield passive plasma lenses (due to loading effect) for identical focusing of short or long homogeneo us electron or positron bunch or Gaussian bunch depending on its length\, charge for stable electron or positron beam propagation in a plasma column \; \n- optimal beam loading for the self-consistent distributions of a dec elerating wakefield of plateau type for a driver-bunch and an accelerating wakefield of plateau type for a witness-bunch during all time of accelera tion\; \n- control of optimal field shape (by loading effect)\, accelerati ng electron or positron bunch in plasma wakefield\; \n- obtaining long ele ctron witness-bunch of good quality (due to loading effect) in plasma wake field accelerator at high transformer ratio\, \n- damping hose instability in plasma wakefield accelerator\;\n- double bunches and twin-bunch in con ditions and places of best bunch stability with plateaus on wakefield in P WFA.\nReferences\n1.W.P. Leemans et al. Phys. Rev. Lett. 113 (2014) 245002 . \n2.V.I.Maslov et al. Problems of Atomic Science and Technology. 6\, 52 (2021). \n3.A.Martinez de la Ossa et al. Phys. Rev. Let. 121\, 064803 (201 8). \n4.G.Loisch et al. J.Phys.: Conf. Ser. 1596\, 012003 (2020).\n\nhttps ://indico.bitp.kiev.ua/event/18/contributions/562/ LOCATION:Bogolyubov Institute for Theoretical Physics Conference Hall URL:https://indico.bitp.kiev.ua/event/18/contributions/562/ END:VEVENT END:VCALENDAR