First Commissioning of the ARES Focusing System and its Possible Upgrade for Accelerator R&D Experiment

The SINBAD (Short INnovative Bunches and Accelerators at DESY) facility at DESY is a dedicated acceleratorresearch and development project for the production of ultra-short electron bunches and development of novelhigh gradient accelerator technology. The ARES linac (Accelerator Research Experiment at SINBAD) is therst infrastructure implemented at SINBAD and has a focus on the generation and characterization of ultra-short, small emittance electron pulses, ultimately aiming at the few femto-second regime. Those ultra-short, lowemittance electron bunches are required, amongst others, for testing laser based novel external injection conceptssuch as laser driven dielectric acceleration structures or plasma wakeelds. This thesis focuses on the optimizationof the required high quality beam transport and focusing from the electron source to the end of the linac or into theexperimental area. As part of the thesis, an algorithm has been developed to optimize the beam transport fromthe photo-injector and through the travelling wave structures by a beam based alignment of the ARES focusingsolenoids. The algorithm was validated against simulations with the ASTRA computer code. A MATLAB userinterface was developed for beam commissioning and data taking at ARES. In various experimental campaignsosets of solenoids were determined and a realignment implemented into the machine. At the end a very goodalignment of the beam trajectory with the magnetic axis along the beamline has been achieved, a major step insuccessful commissioning of the ARES linac. The measurement results, the outcome of the data analysis and thealignment results are presented.As part of the thesis the design of a focusing system was developed. The system would allow for injectioninto a laser wakeeld acceleration experiment at ARES. For such an experiment, ultra-short bunches from ARES,ranging from sub-fs to few fs, would be injected into a plasma cell. The injection of short bunches requires strongtransverse focusing to match the beam into small accelerating channels of the plasma. Transverse matching ofthe electron beam to the plasma channel prevents emittance growth in the nite energy spread beams. Theconceptual design of a nal focus system for injection into a laser plasma experiment at ARES is presented. Theperformance of the design is evaluated by means of ASTRA simulations of the beamline. The design includessensitivity studies on relevant sources of error. The performed error analysis, which could be generalized for anyquadrupole triplet, gives a useful estimate about the performance of the nal focus system and suggests criticalparameters in the implementation of the experiment

Development of measurement frame for detailed measurements of hysteresis cycles of ferromagnetic sheets

This paper describes the electromagnetic design of a new concept of permeameter capable of providing a measurement of the magnetic permeability of sheet strips up to 1.5 mm thick. The measurements are performed in DC. A specific feature of the device is its ability to follow the history of the excitation, representing an ideal tool to experimentally characterize hysteresis cycles as a function of the initial magnetization status of the material. The first preliminary results taken with measurement frame are also presented

Study for the Alignment of Focusing Solenoid of ARES RF Gun and Effect of Misalignment of Solenoid on Emittance of Space Charge Dominated Electron Beam

SINBAD (Short and INnovative Bunches and Accelerators at DESY) facility will host multiple experiments relating to ultra-short high brightness beams and novel experiments with ultra-high gradient. ARES (Accelerator Research Experiment at SINBAD) Linac is an S-band photo injector to produce such electron bunches at around 100 MeV. The Linac will be commissioned in stages with the first stage corresponding to gun commissioning. In this paper, we present studies about the scheme adopted for the alignment of focusing solenoid for the ARES gun. The method is bench marked using ASTRA simulations. Moreover the effect of misalignment of the solenoid on the emittance of space charge dominated scheme and its compensation is also discussed

Beam Dynamics Studies for Beam Focusing and Solenoid Alignment at SINBAD

SINBAD (Short INnovative Bunches and Accelerators at DESY) facility under construction at DESY plans to host several experiments for the production of ultra-short bunches and will be a test facility for high-gradient compact novel acceleration techniques. The ARES (Accelerator Research Experiment at SINBAD) linac is foreseen to produce ultra-short bunches to be injected e.g. into Novel Dielectric Laser Acceleration structures or Laser Wake-Field Acceleration experiments. The work presented in this paper is based on optimization of the focusing system consisting of solenoids for the ARES, which have been studied earlier in detail but is revisited for updated beamline. Moreover tolerances for the possible misalignment of solenoids are presented investigating the effect on the beam properties during the gun commissioning

Design Considerations for Permenant Magnetic Quadrupole Triplet for Matching Into Laser Driven Wake Field Acceleration Experiment at SINBAD

SINBAD (Short and INnovative Bunches and Accelerators at DESY) facility aims to produce ultrashort bunches (sub-fs) at ~100 MeV, suitable for injection into novel accelerators e.g. dielectric Laser acceleration (DLA) and Laser Driven Wakefield acceleration (LWFA). The LWFA experiment demands β functions to be of the order of 1 mm to reduce energy spreads and emittance growth from nonlinearities. Matching such a space charge dominated beam to such constraints with conventional electromagnets is challenging. A Permanent Magnetic Quadrupole (PMQ) triplet is one promising focusing strategy. In this paper, we investigate the performance of a PMQ triplet to fit the requirements of the electron beam properties in a plasma cell and discuss the realizable phase spaces for the LWFA experiment planned at SINBAD

Final Focus System for Injection into a Laser Plasma Accelerator

ARES is an electron linear accelerator at the SINBAD facility at DESY. It aims to deliver reliable high-brightness beams with an energy in the range of 100 to 150 MeV with fs to sub-fs bunch lengths. This is ideal for injection into novel high-gradient acceleration devices, such as dielectric laser accelerators and laser-plasma accelerators (LPAs), which feature fields with fs to ps period. Here, we report the conceptual design of a final focus system for injecting into an LPA experiment at ARES. The design includes permanent magnetic quadrupoles (PMQ), sufficient longitudinal space for collinear laser and electron transport, space for required diagnostics and an LPA setup. The performance of the design is evaluated by means of start-to-end simulations of the linac, focusing system, and injection into the LPA, including sensitivity studies to relevant error sources

Beam Based Alignment of Focusing Solenoids at ARES

ARES is an electron linear accelerator at the SINBAD facility at DESY. It aims to deliver reliable high-brightnessbeams with an energy in the range of 50 MeV to 150 MeVwith fs to sub-fs bunch lengths. This is ideal for injection intonovel high-gradient acceleration devices, such as dielectriclaser accelerators (DLA), accelerator components R&D andmedical applications. The ARES linac has been recentlycommissioned. Here we report the results of beam basedalignment of focusing solenoids of ARES. The alignmentis an important part of commissioning and is crucial for thebeam quality

Status Report of the SINBAD-ARES RF Photoinjector and LINAC Commissioning

The accelerator R facility SINBAD (Short innovative bunches and accelerators at DESY) will drive multiple independent experiments including the acceleration of ultrashort electron bunches and the test of advanced high gradient acceleration concepts. The SINBAD-ARES (Accelerator Research Experiment at SINBAD) setup hosts a normal conducting RF photoinjector generating a low charge electron beam that is afterwards accelerated to 100 MeV by an S-band linac section. The linac as well as a magnetic chicane allow the production of ultrashort pulses with an excellent arrival-time stability. The high brightness beam has then the potential to serve as a test beam for next generation compact acceleration schemes. The setup of the SINBAD-ARES facility will proceed in stages. We report on the current status of the ARES RF gun and linac commissioning

Status Report of the SINBAD-ARES RF Photoinjector and LINAC Commissioning

The accelerator R&D facility SINBAD (Short innovative bunches and accelerators at DESY) will drive multiple independent experiments including the acceleration of ultrashort electron bunches and the test of advanced high gradient acceleration concepts. The SINBAD-ARES (Accelerator Research Experiment at SINBAD) setup hosts a normal conducting RF photoinjector generating a low charge electron beam that is afterwards accelerated to 100 MeV by an S-band linac section. The linac as well as a magnetic chicane allow the production of ultrashort pulses with an excellent arrival-time stability. The high brightness beam has then the potential to serve as a test beam for next generation compact acceleration schemes. The setup of the SINBAD-ARES facility will proceed in stages. We report on the current status of the ARES RF gun and linac commissioning

Commissioning Results and Electron Beam Characterization with the S-Band Photoinjector at SINBAD-ARES

Over the years, the generation and acceleration of ultra-short, high quality electron beams has attracted more and more interest in accelerator science. Electron bunches with these properties are necessary to operate and test novel diagnostics and advanced high-gradient accelerating schemes, such as plasma accelerators and dielectric laser accelerators. Furthermore, several medical and industrial applications require high-brightness electron beams. The dedicated R&D facility ARES at DESY (Deutsches Elektronen-Synchrotron) will provide such probe beams in the upcoming years. After the setup of the normal-conducting, radio-frequency (RF) photoinjector and linear accelerating structures, ARES successfully started the beam commissioning of the RF gun. This paper gives an overview of the ARES photoinjector setup and summarizes the results of the gun commissioning process. The quality of the first electron beams is characterized in terms of charge, momentum, momentum spread and beam size. Additionally, the dependencies of the beam parameters on RF settings are described. All measurement results of the characterized beams fulfill the requirements for operating the ARES linac with this RF photoinjector