Results on the FCC-hh Beam Screen Sawtooth at the Kit Electron Storage Ring Kara

In the framework of the EuroCirCol collaboration [1] (work package 4 "Cryogenic Beam Vacuum System"), the fabrication of the FCC-hh beam screen (BS) prototype has been carried out with the aim of testing it at room temperature on the Karlsruhe Institute of Technology (KIT) 2.5 GeV electron storage ring KARA (KArlsruhe Research Accelerator) light source. The BS prototype was tested on a beamline installed by the collaboration, named as BEam Screen TEstbench EXperiment (BESTEX). KARA has been chosen because its synchrotron radiation (SR) spectrum, photon flux and power match quite well the one foreseen for the 50+50 TeV FCC-hh proton collider. The BS prototype (2 m in length) was manufactured according to the base line design (BD) of the FCC-hh BS. It implements a saw-tooth profile designed to absorb the SR generated at the bending magnets. Also, a laser-ablated anti-electron cloud surface texturing [2] was applied at the BS inner walls. We present here the results obtained at BESTEX and the comparison of the results obtained during irradiation of the saw-tooth profile at different geometric configurations

Detuning Properties of RF Phase Modulation in the Electron Storage Ring KARA

In electron storage rings, it is possible to increase the electron bunch length by applying a phase modulation on the radio frequency accelerating field by choosing appropriate parameters for the modulation. Such a bunch lengthening effect improves beam parameters such as the beam lifetime, which can help us to get better beam stability. The dependence of the bunch lengthening on the modulation frequency, the so-called detuning property, tends to have a peak with asymmetric slopes around it. The modulation amplitude and the beam current also affect the properties of the detuning condition of such bunch lengthening. We have investigated the detuning property with systematic measurements at the electron storage ring KARA. The experimental results agree with the theoretical model and the simulation results

Detuning Properties of RF Phase Modulation in the Electron Storage Ring KARA

In electron storage rings, it is possible to increase the electron bunch length by applying a phase modulation on the radio frequency accelerating field by choosing appropriate parameters for the modulation. Such a bunch lengthening effect improves beam parameters such as the beam lifetime, which can help us to get better beam stability. The dependence of the bunch lengthening on the modulation frequency, the so-called detuning property, tends to have a peak with asymmetric slopes around it. The modulation amplitude and the beam current also affect the properties of the detuning condition of such bunch lengthening. We have investigated the detuning property with systematic measurements at the electron storage ring KARA. The experimental results agree with the theoretical model and the simulation results

Different Operation Regimes at the KIT Storage Ring KARA (Karlsruhe Research Accelerator)

The KIT storage ring KARA operates in a wide energy range from 0.5 to 2.5 GeV. Different operation modes have been implemented at KARA, so far, the double-bend achromat (DBA) lattice with non-dispersive straight sections, the theoretical minimum emittance (TME) lattice with distributed dispersion, different versions of low-compaction factor optics with highly stretched dispersion function. Short bunches of a few ps pulse width are available at KARA. Low-alpha optics has been simulated, tested and implemented in a wide operational range of the storage ring and is now routinely used at 1.3 GeV for studies of beam bursting effects caused by coherent synchrotron radiation in the THz frequency range. Different non-linear effects, in particular residual high-order components of the magnetic field, generated in high-field superconducting wigglers have been studied and cured. Based on good agreement between computer simulations and experiments, a new operation mode at high vertical tune was implemented. The beam performance during user operation as well as at low-alpha regimes has been improved. A specific optic with negative compaction factor was simulated, tested and is in operation

Operation with a Low Emittance Optics at Anka

The electron storage ring at ANKA is designed as a variation of an eightfold DBA structure. Since its commissioning the facility has been operated with zero dispersion in the long straight sections resulting in an emittance of about 100 nmrad. Since mid 2004 ANKA is operated with dispersion distributed over the complete ring thus reducing the emittance to 50 nmrad. Optics calculations and measurements as well as operational experience will be discussed. In order to reduce the losses due to Touschek scattering, a lengthening of the bunches was done by modulation of the main frequency with twice the synchroton frequency. An increase of the lifetime by 5 h could be achieved

Preparations for Beam Tests of a CLIC Damping Wiggler Prototype at ANKA

The Compact Linear Collider (CLIC) will require ultra-low emittance electron and positron beams. The targeted emittance will be achieved by radiative damping in the CLIC damping rings. For an efficient damping high-field short-period superconducting damping wigglers will be employed. In the conceptual design phase of CLIC, the basic layout of these wigglers has been elaborated at CERN. In the course of the CLIC technical feasibility studies a full-scale damping wiggler prototype will be installed and tested in the ANKA storage ring. The device is currently under design and construction at the Budker Institute of Nuclear Physics, Russia. Above the magnetic requirements, the main design challenges for the prototype are scalability –- particularly of the cooling concept –-, modularity and the capability of sustaining a high radiative heat load. The experiments at ANKA aim at a validation of the technical concepts applied to meet these requirements. Beyond that an extended experimental program on beam dynamics and alternative technical solutions is envisaged. This contribution gives an overview over the current status of the project and the further planning