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The European Spallation Source will be driven by a 5 MW linear accelerator, producing 2.86 ms long proton beam pulses with a peak current of 62.5 mA at 14 Hz. Following the source commissioning in 2018 and 2019, the RFQ was successfully conditioned and subsequently commissioned with beam in 2021. In this paper, we will present results of studies on beam matching to the RFQ, both for low and high current beam modes, and will compare these results to model predictions., Proceedings of the 31st International Linear Accelerator Conference, LINAC2022, Liverpool, UK

The European Spallation Source (ESS) aims to build and commission a 2 MW proton linac ready for neutron production in 2025. The normal conducting section of the ESS linac is designed to accelerate a 62.5 mA proton beam to 90 MeV at 14 Hz. The section consists of a microwave ion source, Radio Frequency Quadrupole (RFQ) and 5-tank Drift Tube Linac (DTL). All sections are provided to ESS by in-kind partners across Europe. This paper reports the recent progress on the assembly, installation, testing and commissioning of the ESS normal conducting linac., Proceedings of the 31st International Linear Accelerator Conference, LINAC2022, Liverpool, UK

The European Spallation Source (ESS), currently under construction and initial commissioning in Lund, Sweden, will be the brightest spallation neutron source in the world, when its driving proton linac achieves the design power of 5 MW at 2 GeV. Such a high power requires production, efficient acceleration, and almost no-loss transport of a high current beam, thus making design and beam commissioning of this machine challenging. During the the commissioning time in 2022 a campaign for a full characterisation of the ESS Medium Beta Transport session (MEBT) was carried out. Both transverse optics and longitudinal parameters were measured and compared to simulation, amongst them: buncher cavity tunning, trasnverse emittance and initial twiss parameters. In this paper we present the results and future plans., Proceedings of the 11th International Beam Instrumentation Conference, IBIC2022, Kraków, Poland

The latest beam commissioning phase of the Normal Conducting Linac at ESS delivered a proton beam through the Medium Energy Beam Transport (MEBT) into the first Drift Tube Linac (DTL) tank. The probe beam in MEBT consisted of 3.6 MeV protons of 6 mA, 5 microseconds pulse length and 1 Hz repetition rate. Following the delivery of the components at ESS in Lund in June 2019, the commissioning phase with the MEBT was completed in July 2022. In March 2022, the maximum beam current of 62.5 mA was transported up to the MEBT Faraday cup. This proceeding focuses on the status of MEBT including magnets, buncher cavities, scrapers and beam diagnostics designed and tested in collaboration with ESS Bilbao., Proceedings of the 31st International Linear Accelerator Conference, LINAC2022, Liverpool, UK

The European Spallation Source, currently under construction in Lund, Sweden, will be the brightest spallation neutron source in the world, when the proton linac driver achieves the design power of 5 MW at 2 GeV beam energy. Such a high power requires production, efficient acceleration, and transport of a high current proton beam with minimal loss. This implies in a challenging design and beam commissioning of this machine. The linac features a long pulse length of 2.86 ms at a relatively low repetition late of 14 Hz. The ESS ion source and low energy beam transport are in-kind contributions from INFN-LNS. Beam commissioning of this section started in September 2018 and continued until early July in 2019. This article presents highlights from a campaign of beam characterizations and optimizations during this beam commissioning stage., Proceedings of the 64\textsuperscript{th} ICFA ABDW on High-Intensity and High-Brightness Hadron Beams, HB2021, Batavia, IL, USA

The mechanism of space charge compensation given by the residual gas ionization is a key factor for the emittance containment in the low energy beam transport (LEBT) lines of high intensity hadron injectors. A typical front end including a microwave Ion source, a LEBT and Radio Frequency Quadrupole (RFQ), is equipped with two repellers at each interface to prevent electrons from flowing back, to the source, or forward, to the RFQ. In this paper we will emphasize the importance of the ion Source and LEBT repellers on giving the appropriate boundary conditions for the space-charge compensation building-up mechanism. The theory and simulations are supported by experiments performed in the high intensity facility such as ESS and IFMIF/EVEDA., Proceedings of the 31st International Linear Accelerator Conference, LINAC2022, Liverpool, UK

The European Spallation Source, currently under construction in Lund Sweden, will be a spallation neutron source driven by a superconducting proton linac with a design power of 5 MW. The linac features a high peak current of 62.5 mA and long pulse length of 2.86 ms with a repetition rate of 14 Hz. The normal conducting part of the linac has been undergoing beam commissioning in multiple steps, and the main focus of the beam commissioning has been on bringing systems into operation, including auxiliary ones. In 2022, beam was transported to the end of the first tank of the five-tank drift tube linac. This paper provides a summary of the beam commissioning activities at ESS and the current status of the linac., Proceedings of the 31st International Linear Accelerator Conference, LINAC2022, Liverpool, UK

The Open XAL accelerator physics software platform has been developed through 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 and high-level control (Open XAL also ships with a suite of general-purpose accelerator applications). This paper discusses progress in beam dynamics simulation and updated application framework along with new generic accelerator physics applications. We present the status of the project at each participating facility and a roadmap for continued development., Proceedings of the 13th International Particle Accelerator Conference, IPAC2022, Bangkok, Thailand

The construction of the ESS accelerator is in full swing. Many key components have been delivered from our in-kind partners and installation, testing and commissioning is making remarkable progress. The first machine section to be commissioned with beam is the Normal Conducting Linac (NCL). When completed, a 14 Hz, 2.86 ms proton beam up to 62.5 mA will be transported from the Ion Source, through the Low Energy Beam Transport (LEBT) line, the Radiofrequency Quadrupole (RFQ), the Medium Energy Beam Transport (MEBT) line and the five Drift Tube Linac (DTL) tanks up to 90 MeV where it will be injected in the first superconducting module of the machine. This paper will highlight recent progress across the NCL, present briefly the first commissioning results and discuss the upcoming phases as well as challenges in delivering a machine capable of meeting the requirements for a next generation spallation neutron facility., Proceedings of the 13th International Particle Accelerator Conference, IPAC2022, Bangkok, Thailand

The installation and commissioning of the European Spallation Source is currently underway at full speed, with the goal to be ready for first neutron production by end of 2024. This year we accelerated protons through the first DTL tank. This included the RFQ, 3 buncher cavities in the medium energy beam transport as well as the DTL tank itself as RF elements. At the end of the DTL tank we had a Faraday cup acting as the effective beam stop. This marks the first commissioning when RF matching is required for beam transport. In this paper we discuss the phase scan measurements and analysis of the buncher cavities and the first DTL tank., Proceedings of the 11th International Beam Instrumentation Conference, IBIC2022, Kraków, Poland

The Open XAL accelerator physics software platform is being developed through 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 and high-level control (Open XAL also ships with a suite of general-purpose accelerator applications). This paper discusses progress in beam dynamics simulation, new RF models, and updated application framework along with new generic accelerator physics applications. 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 12th International Particle Accelerator Conference, IPAC2021, Campinas, SP, Brazil

The OpenXAL accelerator physics software platform is being developed through international collaboration among several facilities since 2010. The goal of the collaboration is to establish OpenXAL as a multi-purpose software platform supporting a broad range of tool and application development in accelerator physics and high-level control. This paper discusses progress in beam dynamics simulation and updated application framework along with new generic accelerator physics applications for the ESS branch of the collaboration. We present the current status of the project, a roadmap for continued development and an overview of the future developments needed for ESS future commissioning work., Proceedings of the 17th International Conference on Accelerator and Large Experimental Physics Control Systems, ICALEPCS2019, New York, NY, USA

Beam commissioning of the ion source (IS) and low energy beam transport (LEBT) of the European Spallation Source is ongoing on its site as of writing this paper and continues until June 2019. The LEBT consists of two solenoids with integrated dipole correctors to steer, focus, and match the high current divergent beam out of the IS to the following radio frequency quadrupole (RFQ). It is also equipped with a suite of diagnostics devices to provide a full characterization of the beam for achieving a good transport within the LEBT, optimizing the matching to the RFQ, and also providing references to numerical simulations. This paper presents results of beam characterization campaign from the ongoing beam commissioning period, including the matching at the RFQ interface based on emittance sampling for varied strengths of the solenoids and verification of the linear model for the trajectory and beam envelope., Proceedings of the 10th Int. Particle Accelerator Conf., IPAC2019, Melbourne, Australia

The Open XAL accelerator physics software platform is being developed through an international collaboration among several facilities since 2010. This paper discusses progress in beam dynamics simulation, new RF models, and updated application framework along with new generic accelerator physics applications. 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 10th Int. Particle Accelerator Conf., IPAC2019, Melbourne, Australia

The European Spallation Source (ESS), currently under construction in Lund, Sweden, will be the world’s most powerful linear accelerator driving a neutron spallation source, with an average power of 5 MW at 2.0 GeV. The first protons were accelerated at the ESS site during the commissioning of the ion source and low energy beam transport (LEBT), that started in September 2018 and ran until July 2019. Misalignments of the elements in the LEBT can have a strong impact on the final current transmission of the low energy part. In this paper, we present a way to isolate and measure tilts of the elements and the initial centroid divergence of the source. We also present initial test measurements for the ESS LEBT and discuss how to extend the method to other facilities., Proceedings of the 8th International Beam Instrumentation Conference, IBIC2019, Malmö, Sweden

Beam dynamics simulation of the ion source (IS) and low energy beam transport (LEBT) of the European Spallation Source (ESS) Linac is conducted with TraceWin and IBSimu code. TraceWin allows multi-particle tracking based on a particle-in-cell space-charge solver and is the standard simulation tool of the whole ESS Linac. IBSimu is based on a Vlasov solver and allows to simulate beam extraction from plasma as well as the beam transport in the LEBT. In preparation for beam commissioning of the IS and LEBT in the ESS Linac tunnel, which started in September 2018 and is ongoing as of the timing of writing this paper, the simulation models of the IS and LEBT in these two codes were updated. This paper reports the effort for these updates, including the beam distribution out of the IS, electromagnetic field map of the LEBT solenoid, more realistic aperture structure in the LEBT, as well as updated LEBT solenoids scan simulation., Proceedings of the 10th Int. Particle Accelerator Conf., IPAC2019, Melbourne, Australia

The European Spallation Source (ESS) is currently under construction in the south of Sweden. A highly brilliant neutron source with a 5 MW proton driver will provide state of the art experimental facilities for neutron science. A peak proton beam power in the accelerator of 125 MW means that excellent control over the beam losses becomes essential. The beam physics design of the ESS accelerator is in a TraceWin format, for which we have developed revision control setup, automated regression analysis and deployment of synoptic viewer and tabulated spreadsheets. This allows for an integrated representation of the data that are always kept synchronized and available to other engineering disciplines. The design of the accelerator lattice has gone through several major and minor iterations which are all carefully analysed. In this contribution we present the status of the latest studies which is the first time a complete end-to-end study beginning from the ion source has been performed., Proceedings of the 13th Int. Computational Accelerator Physics Conf., ICAP2018, Key West, FL, USA

The European Spallation Source (ESS), currently under construction in Lund, Sweden, will be a spallation neutron source driven by a proton linac of an unprecedented 5 MW beam power. Such a high power requires its ion source (IS) to produce proton beam pulses at 14 Hz with a high peak current more than 62.5 mA and a long plateau up to §I{3}{ms}. The IS and the following low energy beam transport (LEBT) section were manufactured and tested with beam to meet ESS requirements at INFN-LNS and delivered to ESS towards the end of 2017. Beam commissioning of these two sections on the ESS site has started in September 2018 and will continue until the end of June 2019. This paper provides an overview on this first beam commissioning period at ESS and also presents results of IS characterization and testing on LEBT functionalities., Proceedings of the 10th Int. Particle Accelerator Conf., IPAC2019, Melbourne, Australia

The European Spallation Source (ESS) linac transfer-lines to the target and beam dump are designed for the 2 GeV beam energy. The commissioning and operation of the accelerator will start at a reduced energy of 571 MeV with the high beta part of the linac unpowered. The beam power at this energy is still above 1 MW and a proper transport from the last accelerating cavity to the target is essential. Beam dynamics design of the High Energy Beam Transport (HEBT) and Accelerator to Target (A2T) are studied based on this reduced energy in this paper, including phase advance optimization and rematch. Among the factors which are analyzed are the envelope and beam size on the target which are kept close to their values at 2 GeV and losses along the linac and the transfer lines., Proceedings of the 10th Int. Particle Accelerator Conf., IPAC2019, Melbourne, Australia

Knowledge of the longitudinal beam parameters is important for understanding beam dynamics in linacs. As well as with transverse optics, the settings for the RF cavities have to be established and phase and amplitude seen by the beam must be determined in order to guarantee a stable motion in the longitudinal plane. This work presents an extension of the most widely used phase scan method, relying on time-of-flight, using only transverse positions measured at a few selected BPMs downstream of the cavity being scanned. In principle, the method can be applied both to normal conducting and SC. The suggested method is fast and relatively simple and is capable to provide the values for the cavity transverse misalignment (offsets and tilts) at the same time. It can be a useful part of the initial longitudinal beam tuning., Proceedings of the 8th International Beam Instrumentation Conference, IBIC2019, Malmö, Sweden

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 and high-level control (Open XAL also ships with a suite of general purpose accelerator applications). This paper discusses progress in beam dynamics simulation, new RF models, and updated application framework along with new generic accelerator physics applications. 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 9th Int. Particle Accelerator Conf., IPAC2018, Vancouver, BC, Canada

The ESS linac will deliver an unprecedented 5 MW of average beam power when completed. Beyond the 90 MeV normal conducting front-end, the acceleration is performed using SC structures up to the design energy of 2 GeV. As the ESS will send the beam to a fixed tungsten target, the emittance is not as important a factor as in injectors. However, the losses have to be studied in detail, including not only the average operational loss required to be of less than 1 W/m, but also the accidental losses, losses due to failure and other potentially damaging losses. The commissioning of the ion source and LEBT starts this year and will continue with the RFQ next year. In this contribution we will discuss the beam dynamics aspects and challenges of the ESS linac., Proceedings of the 61\textsuperscript{st} ICFA ABDW on High-Intensity and High-Brightness Hadron Beams, HB2018, Daejeon, Korea

The ESS linac is currently under construction in Lund, Sweden, and once completed it will deliver an unprecedented 5 MW of average power. The ion source and LEBT commissioning starts in 2018 and will continue with the RFQ, MEBT and the first DTL tank next year and up to the end of the fourth DTL tank in 2020. This paper will summarize the commissioning plans for the normal conducting linac with focus on the ion source and LEBT and application development for both commissioning and operation., Proceedings of the 61\textsuperscript{st} ICFA ABDW on High-Intensity and High-Brightness Hadron Beams, HB2018, Daejeon, Korea

Beam commissioning of the proton linac of the European Spallation Source begin in summer, 2018, from the ion source (IS) and low energy beam transport (LEBT), and continues in stages until 2022, when the first beam is sent to its spallation target. This paper presents the plan, status, and highlights of preparation works for the upcoming IS and LEBT beam commissioning., Proceedings of the 9th Int. Particle Accelerator Conf., IPAC2018, Vancouver, BC, Canada

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

A short introduction to the linac beam dynamics code DYNAC will be given. Recently implemented features, such as a Graphical User Interface (GUI), will be presented and benchmarking of the Radio Frequency Quadrupole (RFQ) model will be discussed. Additional planned features to DYNAC and the GUI will be touched upon., Proceedings of the 28th Linear Accelerator Conf., LINAC2016, East Lansing, MI, USA

The commissioning and operations planning for the European Spallation Source is currently being defined. It is foreseen that the ESS will begin to deliver beam on target by mid 2019, something which is urging a well structured and thought through plan both for commissioning and operations. In this paper we will discuss the plans for beam physics operational software, priorities and software services needed during the different stages of beam commissioning., Proceedings of the 7th Int. Particle Accelerator Conf., IPAC2016, Busan, Korea

The European Spallation Source, ESS, uses a linear accelerator to bombard the tungsten target with the high intensity protons beam for producing intense beams of neutrons. The nominal average beam power of the linac is 5~MW with a peak beam power at target of 125~MW. This paper focuses on the beam dynamics design of the ESS linac and the diagnostics elements used for the tuning of the lattice and matching between sections., Proceedings of the 7th Int. Particle Accelerator Conf., IPAC2016, Busan, Korea

Formed in 2010, the Open XAL accelerator physics software platform was developed through an international collaboration among several facilities to establish it as a standard for accelerator physics software. While active development continues, the project has now matured. This paper presents 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 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 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

Making an accurate RF design of any accelerating structure is fundamental to ensure that electromagnetic and beam dynamics requirements will be achieved. This is essential for the most complicated accelerating structures like the drift tube linac: in this case a meticulous design facilitates the RF commissioning too. In this paper the influence of the interfaces and of the field stabilization system on the RF design is analyzed and an advanced design methodology to mitigate field degradation is presented., Proceedings of the 28th Linear Accelerator Conf., LINAC2016, East Lansing, MI, USA

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 field flatness and the layout of the stabilization system in a drift tube linac are strongly dependent on the manufacturing errors that affect the local resonant frequency. In this paper a methodology is presented to study, firstly, the sensitivity of the resonant frequency and of the field flatness to each geometrical parameter of the drift tubes; then a set of tolerances for each parameter is found and a stabilization system layout is defined in order to keep the field flatness within an acceptable limit., Proceedings of the 28th Linear Accelerator Conf., LINAC2016, East Lansing, MI, USA

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

The amplitude detuning has been observed to decrease significantly as the horizontal and vertical tunes are approaching each other. This effect is potentially harmful since it might cause a loss of Landau damping, hence giving rise to instabilities. The measured tune split (Qx-Qy) versus amplitude is several times bigger than what can be explained with linear coupling. In this paper we present studies performed to identify the dominant sources of the non-linear coupling observed in the LHC., Proceedings of the 6th Int. Particle Accelerator Conf., IPAC2015, Richmond, VA, USA

In the beam dynamic design and modelling of the European Spallation Source (ESS) Drift Tube Linac (DTL) simplified models have been used for the focusing and accelerating structures. Since the high current requires precise control of the beam to minimise the losses it is useful to analyse the beam dynamics by using accurate field maps of the focusing and accelerating structures. In this paper the effects of the 3D-field maps on the beam dynamics of the ESS DTL are presented., Proceedings of the 6th Int. Particle Accelerator Conf., IPAC2015, Richmond, VA, USA

Tuning the CLIC Beam Delivery System (BDS), and in particular the final focus, is a challenging task. In simulations without misalignments, the goal is to reach 120~\% of the nominal luminosity target, in order to allow for 10~\% loss due to static imperfections, and another 10~\% loss from dynamic imperfections. Various approaches have been considered to correct the magnet misalignments, including 1-1 correction, dispersion free steering (DFS), and several minimization methods utilizing multipole movers. In this paper we report on the recent advancements towards a feasible tuning approach that reach the required luminosity target in a reasonable time frame., Proceedings of the 5th Int. Particle Accelerator Conf., IPAC2014, Dresden, Germany

Breakdown in the accelerating structures sets an important limit to the performance of the CLIC linear collider. Vacuum degradation and subsequent beam instability are possible outcomes of a breakdown if too much gas is released from the cavity surface. Quantitative data of gas released by breakdowns are provided for copper (milled Cu-OFE, as-received and heat-treated), and molybdenum. These data are produced in a DC spark system based on a capacitance charged at fixed energy, and will serve as a reference for the vacuum design of the CLIC accelerating structures.

The control of the betatron coupling at injection and during the energy ramp is critical for the safe operation of the tune feedback and for the dynamic aperture. In the LHC every fill is preceded by the injection of a pilot bunch with low intensity. Using the injection oscillations from the pilot bunch we are able to measure the coupling at each individual BPM. The measurement is used to calculate a global coupling correction. The correction is based on the use of two orthogonal knobs which correct the real and imaginary part of the difference resonance term f1001, respectively. This method to correct the betatron coupling has been proven successful during the normal operation of the LHC. This paper presents the method used to calculate the corrections and its performance.