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The Open XAL accelerator physics software platform is being developed through an international collaboration among several facilities since 2010 The goal of the collaboration is to establish Open XAL as a multi-purpose software platform supporting a broad range of tool and application development in accelerator physics (Open XAL also ships with a suite of general purpose accelerator applications). This paper discusses progress in beam dynamics simulation, interaction with control system and software organization. We present the current status of the project, a roadmap for continued development and an overview of the project status at each participating facility., Proceedings of the 8th Int. Particle Accelerator Conf., IPAC2017, Copenhagen, Denmark

The linac system at the European Spallation Source (ESS) will deliver 2~GeV protons at 5~MW beam power. The accelerated protons from the linac will be transported to the rotating tungsten target by two bending magnets. A tuning beam dump will be provided at the end of the linac, downstream of the first bending magnet. This tuning dump shall be able to handle at least 12.5 kW of beam power. In this paper, we present the working concept of the tuning dump. The impact of the proton beam induced material damage on the operational loads and service lifetime of the tuning dump is analysed. A number of particle transport and finite-element simulations are performed for the tuning beam modes., Proceedings of the 8th Int. Particle Accelerator Conf., IPAC2017, Copenhagen, Denmark

The modeling of the proton beam in the ESS accelerator starts with a beam distribution as an input to the TraceWin code currently used as the simulation tool. This input is typically a Gaussian distribution, a distribution from other codes, or data from an emittance measurement. The starting point of these simulations is therefore located somewhere along the low energy beam transport (LEBT) close to the ion source. In this paper, we propose to use IBSimu to model the beam extraction from the ion source, which provides an input beam distribution to TraceWin. IBSimu is a computer simulation package for ion optics, plasma extraction, and space charge dominated ion beam transport. We also present a benchmarking of the beam tracking through the LEBT using both these tools, and propose a transition interface to handover the beam distribution from IBSimu to TraceWin., Proceedings of the 8th Int. Particle Accelerator Conf., IPAC2017, Copenhagen, Denmark

The ESS Linac Simulator (ELS) is the model that will be used at the European Spallation Source ERIC in Lund, Sweden, to simulate the transport of the beam envelope for the operations. During the machine restart in August 2015 at the Spallation Neutron Source (SNS) in Oak Ridge, USA, we were able to perform the first benchmarking studies of the ELS. In this paper, we present the results of the phase-scans performed in four RF cavities of the coupled-cavity linac at SNS compared with the same scans simulated in the ELS. The phase of the cavity was modified while the phase of the beam was recorded in two BPMs downstream from the cavity. This measurement was repeated for four independent cavities and the results are compared here with the model, which favourably reproduces the BPM response to the cavity scans., Proceedings of the 7th Int. Particle Accelerator Conf., IPAC2016, Busan, Korea

The construction of the European Spallation Source, ESS, started in summer 2014. At the site in Lund, the accelerator tunnel will be completed at the time of IPAC16, while prototyping and manufacturing or prepara-tions for manpower contributions are going on in more 23 laboratories distributed over the 12 European countries collaborating on the accelerator project. Major technical milestones have been reached include the testing of su-perconducting cavity prototypes of two families to values above design gradients, the first ESS modulator has been tested to 90 kV and the first klystron prototype has been received in April 2016. Equally important developments are taking place at many partner laboratories. The presen-tation will summarize the status of the ESS accelerator project by the time of IPAC16.., Proceedings of the 7th Int. Particle Accelerator Conf., IPAC2016, Busan, Korea

The European Spallation Source front end will deliver a 62.5 mA beam current of 2.8 ms duration at 352 MHz to the downstream linac, which in turn will produce a 5 MW proton beam onto the target. Such unprecedented beam power requires a high quality beam with accurate and stable beam parameters in order to assure low beam losses and safe transport through the linac. In this paper we present advanced tuning methods for the low energy beam transport and the radio frequency quadrupole., Proceedings of the 7th Int. Particle Accelerator Conf., IPAC2016, Busan, Korea

The ESS Linac Simulator (ELS) is the model that will be used at the European Spallation Source ERIC in Lund, Sweden, to simulate the transport of the beam envelope during operations. On August 12th 2015, we had the opportunity to use two hours of beam time in the linac of the Spallation Neutron Source in Oak Ridge to benchmark ELS. In this paper we present the results of the transverse dynamics measurements. Such measurements are obtained upon kicking the beam in the medium-energy beam transport (MEBT) and measuring the effect of the oscillation of the beam centroid in 58 beam position monitors (BPMs). The ELS model and these measurements are in agreement with an average discrepancy of 4% in the superconducting section of the accelerator., Proceedings of the 7th Int. Particle Accelerator Conf., IPAC2016, Busan, Korea

The European Spallation Source will be the worlds brightest neutron source. It will be driven by a 5~MW proton linac that delivers a 2.86~ms pulse at 14~Hz, which means the peak beam power is 125~MW. This requires a careful design of the lattice structures in order to allow for safe and reliable operation of the accelerator. We will discuss some of the design choices and some of the particular challenges that were faced during the design of the ESS lattice., Proceedings of the 57th ICFA Advanced Beam Dynamics Workshop on High-Intensity and High-Brightness Hadron Beams, HB2016, Malmö, Sweden

During the fabrication of an RFQ, deviation from the perfect geometry will occur during assembling, brazing and machining the different parts. These geometrical defects will impact the theoretical inter-vane voltage, given by the beam dynamics, by altering the quadrupolar component as well as adding dipolar terms in the voltage function. Tuners can correct partially the effect of the manufacturing. The study summarizes the effects of the voltage errors on the beam quality in the case of the ESS RFQ with a harmonic analysis of the voltage function. We discuss the acceptable level of voltage errors and associated mechanical tolerances., Proceedings of the 7th Int. Particle Accelerator Conf., IPAC2016, Busan, Korea

The European Spallation Source will offer an unprecedented beam power for spallation sources of 5 MW. The accelerator will deliver a proton beam of 62.5 mA peak current and 2.0 GeV onto the spallation target. Since the technical design report (TDR) was published in 2013, work has continued to further optimize the accelerator design. We report on the advancements in lattice design optimizations after the TDR to improve performance and flexibility, and reduce cost of the ESS accelerator., Proceedings of the 6th Int. Particle Accelerator Conf., IPAC2015, Richmond, VA, USA