Impedance analysis of new PS internal dump design

The High Luminosity Large Hadron Collider (HL-LHC) project at CERN calls for increasing beam intensity in the injector chain. In the Proton Synchrotron (PS), a pre-injector of the LHC, these intensities can result in beam instabilities and potential RF heating of machine components, such that impedance mitigation measures are required. To study these intensity effects, the PS impedance model has been developed and is continuously updated. Each new machine element that is to be added into the accelerator requires an impedance study to minimize its contribution with respect to the machine's overall impedance budget. In such a context, this paper presents the impedance analysis of the new design of the internal beam dump for the PS, showing the design process required to reduce the impedance contribution of this element. Furthermore, the impedance analysis of the currently installed beam dump is analysed in order to compare the impedance contributions of the two designs

A multi-physics approach to simulate the RF heating 3D power map induced by the proton beam in a beam intercepting device

The project High Luminosity Large Hadron Collider (HL-LHC) calls for a streaking beam intensity and brightness in the LHC machine. In such a scenario, beam-environment electromagnetic interactions are a crucial topic: they could lead to uneven power deposition in machine equipment. The resulting irregular temperature distribution would generate local thermal gradients, this would create mechanical stresses which could lead to cracks and premature failure of accelerator devices. This work presents a method to study this phenomenon by means of coupled electro-thermomechanical simulations. Further, an example of application on a real HL-LHC device is also discussed

Analysis on the mechanical effects induced by beam impedance heating on the HL-LHC target dump injection segmented (TDIS) absorber

The High Luminosity Large Hadron Collider (HL-LHC) Project at CERN calls for increasing beam brightness and intensity. In such a scenario, critical accelerator devices need to be redesigned and rebuilt. Impedance is among the design drivers, since its thermo-mechanical effects could lead to premature device failures. In this context, the current work reports the results of a multiphysics study to assess the electromagnetic and thermo-mechanical behaviour of the Target Dump Injection Segmented (TDIS). It first discusses the outcomes of the impedance analysis performed to characterise the resistive wall and the high order resonant modes (HOMs) trapped in the TDIS structures. Then, their RF-heating effects and the related temperature distribution are considered. Finally, mechanical stresses induced by thermal gradients are studied in order to give a final validation on the design qualit

Design of the new proton synchrotron booster absorber scraper (PSBAS) in the framework of the large hadron collider injection upgrade (LIU) project

The Large Hadron Collider (LHC) Injector Upgrade (LIU) Project at CERN calls for increasing beam intensity for the LHC accelerator chain. Some machine components will not survive the new beam characteristics and need to be rebuilt for the new challenging scenario. This is particularly true for beam intercepting devices (BIDs) such as dumps, collimators, and absorber/scrapers, which are directly exposed to beam impacts. In this context, this work summarizes conceptual design studies on the new Proton Synchrotron Booster (PSB) Absorber/Scraper (PSBAS), a device aimed at cleaning the beam halo at the very early stage of the PSB acceleration. This paper outlines the steps performed to fulfill the component design requirements. It discusses thermomechanical effects as a consequence of the beam-matter collisions, simulated with the FLUKA Monte Carlo code and ANSYS® finite element software; and the impedance minimization study performed to prevent beam instabilities and to reduce RF-heating on the device

Human exploration of cis-lunar space via assets tele-operated from EML2 (HECATE)

This paper presents the preliminary design of the international space mission HECATE (Human Exploration of Cis-lunar space via Assets Tele-operated from EML-2), aimed at exploring the far side of the Moon via tele-robotic activities during the 2020s. The exploration is realized by astronauts from HOPE (Human Orbiting Protected Environment), a space habitat in a halo orbit around the Earth-Moon Lagrange Point 2, a critical staging location for future robotic and human deep space missions. Inside the habitat, astronauts have access to tele-robotic hardware and instruments, used to tele-operate rovers and scientific equipment on the surface of the Moon. Plans to resupply and maintain HOPE for future missions, using a solar electric tug, are given. Ultimately, HOPE represents an energetically favorable intermediate locations for missions to Mars, Near-Earth Asteroids, and beyond

A Thermomechanical and Electromagnetic Approach For The Design Of High-Intensity Accelerator Components

At the European Council for Nuclear Research (CERN) two projects call for an upgrade of the laboratory particle accelerators to find new physics results: the High-Luminosity Large Hadron Collider (HL-LHC) and the LHC Injection Upgrade (LIU). In this context, beam characteristics such as intensity and stored energy will be doubled. Some of the current accelerator components cannot safely perform their main tasks with these new conditions. As an example, it was demonstrated that the majority of the devices responsible for partially or totally absorbing the beam, the so-called beam intercepting devices (BIDs), have to be redesigned to face the new challenging scenario. These devices, because of their specific functional requirements, usually, have strong electromagnetic interaction with the beam, i.e. high impedance. They are among the strongest impedance sources in the CERN accelerators. Devices with high impedance could generate beam instabilities or they could be overheated because of RF-heating. Thus, at CERN, an impedance minimization campaign for the new BIDs was started, and this thesis reports the results of the campaign. In particular, the manuscript analyzes the impedance of LIU and HL-LHC devices via simulations and measurements. It defines a series of guidelines for minimizing the device impedance and shows examples of the successful application of these guidelines. Furthermore, the impedance induced heating thermo-mechanical effects are also discussed, a new method to simulate them is developed and successfully benchmarked against experimental data. Finally, the manuscript tackles the problem of determining the wakefield and the impedance induced heating of two counterrotating beams passing in the same vacuum chamber. On this topic, some extensions to the present theory are reported

Design of low-impact impedances devices: the new proton synchrotron booster absorber scraper (PSBAS)

At CERN the HL-LHC (High Luminosity Large Hadron Collider) and the LIU (LHC Injection Upgrade) projects call for an increase in beam parameters such as energy, intensityand brightness. To achieve this goal the whole accelerator complex will be upgraded. Systems, equipment and devices need to be redesigned and rebuilt accounting for the demanding new beam features. In this framework device impedance is a key parameter. It is essential to evaluate and to minimize the impedance of the component during its early design phase. This avoids beam instabilities and minimizes beam losses and induced heating. In this paper we outline general guidelines for a low-impedance design and we show how to implement them in a real case, taking as example the design of the new Proton Synchrotron Booster Absorber Scraper (PSBAS). This is a key component aimed to remove the beam halo at the beginning of the LHC accelerator chain

Analysis on the thermal response to beam impedance heating of the post LS2 Proton Synchrotron beam dump

The High Luminosity Large Hadron Collider (HL-LHC) and the LHC-Injection Upgrade (LIU) projects at CERN are upgrading the whole CERN accelerators chain to increase beam brightness and intensity. In this scenario, some critical machine components have to be redesigned and rebuilt. Due to the increase in beam intensity, minimizing the electromagnetic interaction between the beam and devices is a crucial design task. Indeed, these interactions could lead to beam instabilities and excessive thermo-mechanical loadings in the device. In this context, this paper presents an example of multi-physics study to investigate the impedance related thermal effects. The analysis is performed on the conceptual design of the new proton synchrotron (PS) internal dump

High intensity proton beam impact at 440 GeV/c on Mo and Cu coated CfC/graphite and SiC/SiC absorbers for beam intercepting devices

Beam Intercepting Devices (BIDs) are essential protection elements for the operation of the Large Hadron Collider (LHC) complex. The LHC internal beam dump (LHC Target Dump Injection or LHC TDI) is the main protection BID of the LHC injection system; its main function is to protect LHC equipment in the event of a malfunction of the injection kicker magnets during beam transfer from the SPS to the LHC. Several issues with the TDI were encountered during LHC operation, most of them due to outgassing from its core components induced by electron cloud effects, which led to limitations of the injector intensity and hence had an impact on LHC availability. The absorbing cores of the TDIs, and of beam intercepting devices in general, need to deal with high thermo-mechanical loads induced by the high intensity particle beams. In addition, devices such as the TDI — where the absorbing materials are installed close to the beam, are important contributors to the accelerator impedance budget. To reduce impedance, the absorbing materials that make up the core must be typically coated with high electrical conductivity metals. Beam impact testing of the coated absorbers is a crucial element of development work to ensure their correct operation. In the work covered by this paper, the behaviour of several metal-coated absorber materials was investigated when exposed to high intensity and high energy proton beams in the HiRadMat facility at CERN. Different coating configurations based on copper and molybdenum, and absorbing materials such as isostatic graphite, Carbon Fibre Composite (CfC) and Silicon Carbide reinforced with Silicon Carbide fibres (SiC-SiC), were tested in the facility to assess the TDI's performance and to extract information for other BIDs using these materials. In addition to beam impact tests and an extensive Post Irradiation Examination (PIE) campaign to assess the performance of the coatings and the structural integrity of the substrates, extensive numerical simulations were carried out.Beam Intercepting Devices (BIDs) are essential protection elements for the operation of the Large Hadron Collider (LHC) complex. The LHC internal beam dump (LHC Target Dump Injection or LHC TDI) is the main protection BID of the LHC injection system; its main function is to protect LHC equipment in the event of a malfunction of the injection kicker magnets during beam transfer from the SPS to the LHC. Several issues with the TDI were encountered during LHC operation, most of them due to outgassing from its core components induced by electron cloud effects, which led to limitations of the injector intensity and hence had an impact on LHC availability. The absorbing cores of the TDIs, and of beam intercepting devices in general, need to deal with high thermo-mechanical loads induced by the high intensity particle beams. In addition, devices such as the TDI - where the absorbing materials are installed close to the beam, are important contributors to the accelerator impedance budget. To reduce impedance, the absorbing materials that make up the core must be typically coated with high electrical conductivity metals. Beam impact testing of the coated absorbers is a crucial element of development work to ensure their correct operation. The behaviour of several metal-coated absorber materials was investigated when exposed to high intensity and high energy proton beams in the HiRadMat facility at CERN. Different coating configurations based on copper and molybdenum, and absorbing materials such as isostatic graphite, Carbon Fibre Composite (CfC) and Silicon Carbide reinforced with Silicon Carbide fibres (SiC-SiC), were tested in the facility to assess the TDI's performance and to extract information for other BIDs using these materials. In addition to beam impact tests and an extensive Post Irradiation Examination (PIE) campaign, extensive numerical simulations were carried out