Search

10th International Particle Accelerator Conference, IPAC’19, Melbourne, Australia, 19 May 2019 - 24 May 2019; Geneva, Switzerland : JACoW Publishing 2286-2290 (2019). doi:10.18429/JACOW-IPAC2019-WEZPLS2, Beam driven wakefield acceleration (PWFA) schemes in plasmas are among the most promising candidates for novel, compact accelerators. Several aspects of PWFA are under investigation at the Photoinjector Test facility at DESY in Zeuthen (PITZ). One of the main characteristics of these accelerators is the ratio between field strength usable for acceleration and decelerating field strength in the driver bunch, the so called transformer ratio. To reach high transformer ratios usually shaped bunches, e.g. with ramped current profiles are employed as drivers. The so-called self-modulation instability, which causes transverse modulation of a bunch longer than the plasma wavelength, is proposed as a means of supplying short driver bunches for proton-driven PWFA. This talk will give an overview on experimental results in these two aspects of PWFA at PITZ with a focus on the production of electron bunches enabling high transformer ratio acceleration by shaping the photocathode laser pulses of a photoinjector and the demonstration of high transformer ratio PWFA. Simulations and further developments on the shaping techniques, allowing highly flexible electron bunches for future plasma wakefield accelerators are also presented., Published by JACoW Publishing, Geneva, Switzerland

10th International Particle Accelerator Conference, IPAC’19, Melbourne, Australia, 19 May 2019 - 24 May 2019; Geneva, Switzerland : JACoW Publishing 3612-3615 (2019). doi:10.18429/JACOW-IPAC2019-THPGW016, The Photo Injector Test Facility at DESY in Zeuthen (PITZ) carries out studies of beam-driven plasma wakefield acceleration (PWFA). The facility possesses a flexible photocathode laser beam shaping system and a variety of diagnostics including a high-resolution dipole spectrometer and an rf deflector which enables the observation of the longitudinal phase space of electron beams after their passage through a plasma. Two plasma sources are available: a gas discharge plasma cell and a photoionized lithium vapor plasma cell. Studies at PITZ include investigations of the self-modulation instability of long electron beams and the high transformer ratio, i.e., the ratio between the maximum accelerating field behind the drive beam and the decelerating field within the beam. This overview includes the experimental results and plans for future experiments., Published by JACoW Publishing, Geneva, Switzerland

9th International Particle Accelerator Conference, IPAC'18, Vancouver, Canada, 29 Apr 2018 - 4 May 2018; Geneva, Switzerland : JACoW Publishing 1648-1650 (2018). doi:10.18429/JACoW-IPAC2018-TUPML047, The transformer ratio, the ratio between maximum accelerating field and maximum decelerating field in the driving bunch of a plasma wakefield accelerator (PWFA), is one of the key aspects of this acceleration scheme. It not only defines the maximum possible energy gain of the PWFA but it is also connected to the maximum percentage of energy that can be extracted from the driver, which is a limiting factor for the efficiency of the accelerator. Since in linear wakefield theory a transformer ratio of 2 cannot be exceeded with symmetrical drive bunches, any ratio above 2 is considered high. After the first demonstration of high transformer ratio acceleration in a plasma wakefield at PITZ, the photoinjector test facility at DESY, Zeuthen site, limiting aspects of the transformer ratio are under investigation. This includes e.g. the occurrence of bunch instabilities, like the transverse two stream instability, or deviations of the experimentally achieved bunch shapes from the ideal., Published by JACoW Publishing, Geneva, Switzerland

The EuPRAXIA project aims at designing the world’s first accelerator based on plasma-wakefield advanced technique, which can deliver a 5 GeV electron beam with simultaneously high charge, low emittance and low energy spread to user’s communities. Such challenging objectives can only have a chance to be achieved when particular efforts are dedicated to identify the subsequent issues and to find the way to solve them. Many injection/acceleration schemes and techniques have been explored by means of thorough simulations in more than ten European institutes to sort out the most appropriate ones. The specific issues of high charge, high beam quality and beam extraction then transfer to the user’s applications, have been tackled with many innovative approaches*. This article highlights the different advanced methods that have been employed by the EuPRAXIA collaboration and the preliminary results obtained. The needs in terms of laser and plasma parameters for such an accelerator are also summarized., Proceedings of the 10th Int. Particle Accelerator Conf., IPAC2019, Melbourne, Australia