D - Beam Dynamics

Beam Dynamics

The high beam currents aimed for in ERLs in combination with the recirculating design of the beamline pose great demands on the planning of beam dynamics in such accelerators. In an ERL, space charge can play an important role at injection and during deceleration. In combination with other effects, like an internal target, this can cause the formation of a beam halo. Collimation of such a halo at dedicated positions is vital to prevent possible loss of superconductivity through energy deposited by halo particles into the superconducting accelerating structures. In addition, wake fields can induce beam breakup instabilities that can be modified at lower energies by space charge. Project Area D of AccelencE concentrates on the one hand on establishing a stable ERL operation of the S-DALINAC. On the other hand beam instablities and state of the art simulation methods are of special interest.

Research topics

  • Strahldynamik und -diagnose am Energie-rückgewinnenden S-DALINAC

    Beam Diagnostics at the Energy-Recovering S-DALINAC

    This project connects investigations of the beam dynamics of the S-DALINAC with new beam diagnostics, which is needed to verify the simulations. The beam dynamics studies consist of simulations of the beam transport, which are used to determine suitable accelerator setpoints. Furthermore, the phenomenon of transverse beam breakup is studied in order to understand the dependence of the maxium possible beam current of the beam energy and the S-DALINAC operation mode. Finally, the beam diagnostics are being extended by the addition of several emittance measurement stations based on optical transition radiation. The emittance measurements allow to make sure that the beam dynamics simulations are based on appropriate starting conditions and describe the beam transport properly.

    Author: M.Sc. Jonas Pforr

    Supervisors: Prof. Dr. Dr. h.c. mult. Norbert Pietralla, JProf. Dr. Florian Hug

  • Entwicklung einer ERL-Strahldiagnose und Untersuchungen zur Stabilität des ERL-Betriebs am S-DALINAC (Match)

    Development of an ERL beam diagnosis and studies on the stability of ERL operation at the S-DALINAC (match)

    The aim of this project is to develop a 6 GHz cavity beam position monitor for the multi-turn ERL operation. With this monitor, the simultaneous position measurement of both the accelerated and the decelerated beam is envisaged. Investigations of the stabilities and tolerances of the magnetic fields and the RF control are carried out by simulating the transversal and longitudinal beam dynamics in ERL mode.

    Author: M.Sc. Manuel Dutine

    Supervisors: Prof. Dr. Dr. h.c. mult. Norbert Pietralla, Prof. Dr. Joachim Enders

  • Wakefield-Simulationen mit extrem kurzen Elektronenbunchen für zukünftige FELs (Match)

    Wakefield simulations with extremely short electron bunches for future free electron lasers (match)

    Author: Dr. David Bizzozero

    Supervisor: Prof. Dr.-Ing. Thomas Weiland

  • Inbetriebnahme des mehrfach rezirkulierenden ERL-Modus am S-DALINAC und Untersuchungen zu hoher Energieauflösung und hohem Strahlstrom im ERL-Betrieb (Match)

    Initial operation of the multi-turn ERL-Mode at the S-DALINAC and investigations on high energy resolution and high beam current during ERL operation (match)

    The superconducting recirculating electron accelerator S-DALINAC at TU Darmstadt is capable to run as an Energy Recovery Linac (ERL). In order to run it in the twofold recirculating ERL mode, extensive 6D beam dynamics simulations will be performed. One focus is to optimize the longitudinal phase space and to provide a low energy spread at an intended interaction point. In order to determine this energy spread, a dispersion based diagnostic unit will be built. In addition, studies are carried out to achieve a high beam current in ERL mode.

    Author: M.Sc. Felix Schließmann

    Supervisors: Prof. Dr. Dr. h.c. mult. Norbert Pietralla, Prof. Dr. Joachim Enders

  • Strategien zur Vermeidung von transversalem Strahlzerfall in rezirkulierenden Elektronenbeschleunigern (Match)

    Strategies for avoiding transverse beam break-up in recirculating electron accelerators (match)

    Author: M.Sc. Ruben Grewe

    Supervisors: Prof. Dr. Dr. h.c. mult. Norbert Pietralla, Prof. Dr. Joachim Enders

  • Untersuchung von Raumladungseffekten und Microbunching-Instabilität am MESA

    Study of Space Charge Effects and Microbunching Instability in MESA

    Space charge (SC) and microbunching instability (MBI) studies are important for low energy, multi-turn machines like MESA carrying high current, high brilliance short electron bunches. For such electron bunches traversing through bends, as for example the recirculation arcs of an energy recovery linac (ERL), SC might result in beam-phase space degradation. SC modifies the electron transverse dynamics in dispersive regions along the beam line and cause emittance growth for mismatched beams and longitudinal space charge together with dispersion can lead to amplification of the initial shot noise by density modulations along the beamline, which is known as MBI.

    Author: M.Sc. Aamna Khan

    Supervisors: Prof. Dr. Oliver Boine-Frankenheim, Prof. Dr. Kurt Aulenbacher

  • Strahldynamik und Kollimation hinter MAGIX am MESA

    Beam dynamics and collimation following MAGIX at MESA

    The MESA Internal Gas Target Experiment (MAGIX) is the currently developed internal target at MESA.

    At energies up to 105 MeV and 1 mA c.w. beam current in energy recovery mode, it allows precision measurements in the search for dark photons, to investigate on the proton form factor and the astrophysical S-factor.

    A halo forms through scattering of the electron beam on the target and beam losses occur in the following accelerator sections.

    The subject of this thesis is the investigation on impacts of the beam-target-interaction on the beam and the behavior of the halo during the transport to the following linac module.

    Aspects of machine protection due to beam losses and subsequently emerging ionizing radiation are furthermore included.

    Author: M.Sc. Ben Ledroit

    Supervisor: Prof. Dr. Kurt Aulenbacher

  • Strahldynamisches Verhalten der MESA SRF-Strukturen im rezirkulierenden Modus

    Beam dynamical behaviour of the MESA SRF-Structures under recirculating operation

    A potential limit to maximum beam current for MESA is the transverse beam breakup (BBU) instability induced by dipole Higher Order Modes (HOMs). These modes can be excited by bunches passing through the cavities off axis. Following bunches are then deflected by the HOMs, which results in even larger offsets for recirculated bunches. This feedback can even lead to beam loss. Simulation studies of BBU limits for MESA as well as measurements of the HOMs in the cold (2K) cryomodules are part of the project.

    Author: M.Sc. Christian Stoll

    Supervisors: Dr. Robert Heine, JProf. Dr. Florian Hug