High Energy Beam Transport Line Research Articles

Shielding optimization to reduce the radiation field in the accelerator systems of IFMIF-DONES

In IFMIF-DONES, a deuteron beam will impinge on a flowing liquid lithium target, resulting in an intense neutron source. Other radiation sources will also arise due to the interactions between deuterons and the beam facing accelerator components. These radiation fields may cause some negative effects, such as damage to equipment or the generation of residual radiation sources. The characterization and mitigation of all the radiation sources are crucial for a safe operation and maintenance of the facility. In this study, the optimization and/or implementation of some radiation shields located in critical areas is considered to reduce the doses during operation and shutdown. Three scenarios are assessed: (i) shielding optimization of the High-Power Beam Dump for the accelerator commissioning, (ii) shielding optimization for the scraper of the High Energy Beam Transport line and the Fast Safety Isolation Valves, and (iii) shielding implementation to reduce the radiation transmission through Heating, Ventilation, and Air Conditioning wall penetrations. Radiation maps of the biological dose and the dose to silicon are computed, showing the impact of such shielding elements.

Engineering design status of IFMIF-DONES High Energy Beam Transport line and Beam Dump system inside the TIR and RIZ

IFMIF-DONES (International Fusion Materials Irradiation Facility – DEMO Oriented Neutron Source) is a fusion materials testing facility that is currently being designed under the framework of a work package of the EUROfusion Consortium. It will use a 125mA at 40MeV deuteron beam to generate a high neutron flux through Li(d,xn) stripping nuclear reactions in a liquid lithium target. The High Energy Beam Transport line (HEBT), the most upstream system of the IFMIF-DONES accelerator, is responsible for the guidance and shaping of the beam towards the target. Additionally, during commissioning periods, the HEBT is also responsible for diverting the beam, through the Beam Dump Transport Line, to the Beam Dump for testing purposes. The HEBT is spread along different rooms and zones: the Accelerator Vault, the Radiation Interface Zone (RIZ), and Target Interface Room (TIR). The engineering design of the HEBT components situated within the TIR and RIZ has been updated to satisfy new requirements, with a focus on ensuring the protecting of the Fast Isolation Valve (FIV) from the backscattered radiation from the target. These modifications include relocating the FIV from the TIR to the RIZ, adjusting the building layout to accommodate the new FIV module, configuring an enclosure cabinet for the RIZ, and adding local shielding to extend the lifetime of the FIV seal actuators. This work describes the current status of these TIR and RIZ engineering design, including radioprotection, commissioning and maintenance plan, beam diagnostics devices, beam dynamics and new remote handling approaches, as well as the layout and integration of the required components along the beamline. The TIR and RIZ are critical areas for IFMIF-DONES, and their design and operation must be compliant with functional, reliability and safety requirements. The updated design addresses potential issues and enhances the facility’s overall functionality.

Status of the engineering design of the IFMIF-DONES high energy beam transport line and beam dump system

IFMIF-DONES plant [1] (International Fusion Materials Irradiation Facility – DEMO Oriented Neutron Source) is currently being developed under the framework of a work package of the EUROfusion Consortium. It will be a facility located at the south of Spain in Granada. Its objective and main goal is the testing and qualification of fusion materials by the generation of a neutron flux with a broad energy distribution covering the typical neutron spectrum of a (D-T) fusion reactor. This is achieved by the Li (d,xn) nuclear reactions occurring in a liquid lithium target where a 40 MeV at 125 mA deuteron beam with a variable beam footprint between 200 mm × 50 mm and 100 mm × 50mm collides. The Accelerator Systems is in charge of providing such high energy deuterons to produce the required neutron flux. The High Energy Beam Transport line (HEBT) is the last subsystem of the IFMIF-DONES accelerator, and its main functions are to guide the deuteron beam towards the liquid lithium target and to shape it with the required rectangular reference beam footprints. The HEBT system includes a Beam Dump devoted to stop the beam during commissioning and start-up phases. The present work details the present status of the HEBT engineering design, including beam dynamics, vacuum configuration, radioprotection, beam diagnostics devices and remote handling analyses performed detailing the layout and integration of required components through-out the beamline.

Design and manufacturing of the combined quadrupole and corrector magnets for the LIPAc accelerator high energy beam transport line

The International Fusion Materials Irradiation Facility (IFMIF) is a project aiming to investigate candidate materials to be used in the most exposed zones of future fusion reactors. The linear IFMIF prototype accelerator (LIPAc), presently under commissioning in Rokkasho, Japan, is a prototype of the frontend section of one of the IFMIF accelerators. Eight quadrupole magnets, six pairs of corrector magnets and one dipole are responsible for generating the magnetic fields needed for a proper beam handling along the 10 m long LIPAc high energy beam transport line, which connects the end of the superconducting radio frequency Linac with the beam dump. A novel design of combined magnets with the correctors integrated in the quadrupole poles is chosen for compactness reasons. The different stages of the production of the combined magnets, from the magnetic and mechanical design to their manufacturing and testing, including exhaustive characterization of the magnetic performance are described in this work. The results from the tests revealed the quality of the magnetic field produced. The materials selection was done carefully, to withstand the high levels of ionizing radiation expected at the magnet locations. This paper focuses on the activities performed in Europe, before sending the magnets to Japan for their installation and commissioning at the Rokkasho site.

The IFMIF-DONES fusion oriented neutron source: evolution of the design

IFMIF-DONES is a powerful neutron irradiation facility for the study and qualification of materials planned as part of the European roadmap to fusion-generated electricity. Its main goal is to study properties of materials under severe irradiation in a neutron field similar to the one in a fusion reactor first wall. It is a key facility to prepare for the construction of the DEMO power plant envisaged to follow ITER. The decision to start the construction of IFMIF-DONES is expected imminent. In this paper we present and discuss several key technical studies and decisions to improve and optimize the engineering design of IFMIF-DONES which were carried out as part of the activities in the framework of the EUROfusion Early Neutron Source work package (2015–2020). The following topics are discussed in this paper: the new layout of the IFMIF-DONES SRF LINAC accelerator and high-energy beam transport line, 7Be impurity management approach for the lithium loop, a maintainable test cell concept, a revised layout of the access cell for the remote maintenance operations, and facilities for complementary experiments.

Status and future developments of the Linear IFMIF Prototype Accelerator (LIPAc)

LIPAc is the Linear IFMIF Prototype Accelerator developed within the framework of the IFMIF project under the Broader Approach (BA) agreement signed between EURATOM and the Japanese Government in 2007. The IFMIF accelerator aims to provide an accelerator-based D-Li neutron source to produce high intensity neutron fluxes with appropriate energy spectrum in order to characterize materials envisioned for future fusion reactors. Because the IFMIF accelerator has to reach unprecedented performances, the feasibility is being tested through the design, manufacturing, installation, commissioning and testing activities of a 1:1-scale prototype accelerator, namely LIPAc, from the injector to the first cryomodule together with the High Energy Beam Transport line and the High Power Beam Dump. After outstanding results obtained in 2019, the LIPAc project has entered 2020 in the preparation of the third commissioning stage, i.e., validation in continuous-wave mode of the complete accelerator up to 5 MeV with its final beam dump. The validation until the nominal energy of 9 MeV will be made after the completion of cryomodule assembly. After a brief overview of the goals already achieved in the framework of the IFMIF/EVEDA program, this paper will present a synthesis of the results that have been obtained so far with the LIPAc accelerator as well as the future developments planned beyond 2020.

Design of the HEBT components inside TIR room of the IFMIF DONES facility

The High Energy Beam Transport (HEBT) line components maintenance are to be conducted during twice yearly shutdown “beam off” periods, one 3-day shutdown and the main “beam off” shutdown period (annual preventive maintenance), which includes the necessary cooling and warming time, all totalling 20 days. Due to the radiation doses calculated and its subsequent radiation zone classification, technically challenging maintenance activities will need to be performed in the Accelerator Systems (AS) and particularly in the HEBT section located inside Target Interface Room (TIR). Thus, all HEBT components inside TIR must be designed to be maintained and replaced by Remote Handling (RH). In order to fulfil the RH requirements, a modularity approach intends to divide HEBT line section into independent large replacement units (LRUs), with localized interfaces. Splitting this section in three modules allows, first, the identification of faulty components more easily and secondly, reduces time needed for their replacement. In addition, the design of these modules has been performed to comply with beam dynamics, vacuum, building, RAMI and positioning requirements established for this section of the HEBT. As a result of the work done, the conclusions concerning the whole design process are summarized at the end of the paper.

Remote handling maintenance of beam dump in IFMIF-DONES

IFMIF-DONES aims at providing high-energy deuterons to produce a neutron flux to test materials. The accelerator stops the pulsed beam at a low duty cycle in the Beam Dump, which is a relevant component of the High Energy Beam Transport line. The cartridge of the Beam Dump absorbs a beam of charged particles during DONES accelerator commissioning and start-up phases after a shutdown. The cartridge is contained for security reasons in a shielding given its high activation, which remains for a long time. Deterioration of this component is due to heating cycles, radiation and corrosion caused by the cartridge cooling water. Thereby, Beam Dump has been classified as 3rd class Remote Handling component. It means that there is no scheduled maintenance for this component, but Remote Handling operations are required in case of failure. Remote equipment is mandatory when the Beam Dump shielding is open due to the high radiation levels. This work presents the maintenance operations to replace the Beam Dump cartridge. It includes the sequence and description of the procedures, equipment and tools necessary to meet the project requirements.

Design, manufacturing and tests of the LIPAc high energy beam transport line

The International Fusion Materials Irradiation Facility (IFMIF) is a projected accelerator-based, D-Li neutron source for fusion reactor materials qualification. LIPAc (Linear IFMIF Prototype Accelerator) is an accelerator aiming to generate a 125 mA, 9 MeV continuous wave deuteron beam, which is currently being commissioned in Rokkasho (Japan) with the objective of validating the IFMIF accelerator design.In LIPAc, a 10 m long High Energy Beam Transport line (HEBT) will connect the exit of the superconducting linac to the beam dump (BD). The HEBT line must accommodate the diagnostics for beam characterization and open the beam at the end to allow its stopping at the BD. The line contains several magnets to control the beam shape and its trajectory, maintaining beam losses below 1 W m−1 along the beamline to limit activation of surrounding elements and allow hands-on maintenance.In this work, the LIPAc HEBT line project is described since its origins. A summary of the beam dynamics calculations and other studies (vacuum, radioprotection, assembly, alignment) that led to the conceptual design of the line is done. After that, the detailed design of the line is presented, justifying the main design decisions taken and finally, the manufacturing and procurement process and the acceptance tests performed are summarized.

Nonintrusive measurement of time-resolved emittances of 1-GeV operational hydrogen ion beam using a laser comb

We proposed and demonstrated a novel technique to measure time-resolved transverse emittances of the hydrogen ion (${\mathrm{H}}^{\ensuremath{-}}$) beam in a 1-GeV high-power accelerator. The measurement is performed in a nonintrusive manner by using a laser comb---laser pulses with controllable multilayer temporal structure. The technique has been applied to the transverse emittance measurement of a 1-GeV ${\mathrm{H}}^{\ensuremath{-}}$ beam in the Spallation Neutron Source high energy beam transport line. More than 20 time-resolved emittances have been simultaneously determined within a macropulse, a single minipulse, or a single bunch of the 1.4-MW neutron production ${\mathrm{H}}^{\ensuremath{-}}$ beam from a single measurement.

Mitigation of beam losses in LANSCE linear accelerator

The LANSCE accelerator has been in operation for nearly five decades. During this period, it was transformed from a 0.8 MW average proton beam power machine used primarily for the study of meson physics, to a multi-user high-power facility for fundamental research and national security applications, concurrently delivering beams to five distinct experimental areas. Minimization of beam losses in multi-beam application is a key issue for effective operation of accelerator facility. This paper summarizes recent experimental results in understanding and lowering of beam losses in LANSCE linear accelerator and high-energy beam transport lines.

Preliminary design of the HEBT of IFMIF DONES

IFMIF-DONES (International Fusion Materials Irradiation Facility – DEMO Oriented Neutron Source) is currently being developed in the frame of the EUROfusion Early Neutron Source work package (WPENS) and will be an installation for fusion material testing, that will generate a flux of neutrons of 1018 m−2s−1 with a broad peak at 14 MeV by Li(d,xn) nuclear reactions thanks to a 40 MeV deuteron beam colliding on a liquid Li flow.The accelerator system is in charge of providing such high energy deuterons in order to produce the expected neutron flux. The High Energy Beam Transport line (HEBT) is the last subsystem of the accelerator and its main functions are to guide the deuteron beam towards the Lithium target and to shape it by the use of magnetic elements to the reference beam footprint at the Lithium Target.The present work summarizes the current status of the HEBT design, including beam dynamics, vacuum, radioprotection, diagnostics and remote handling studies performed, along with the layout and integration of the line.

Validation of the Linear IFMIF Prototype Accelerator (LIPAc) in Rokkasho

For the development of the International Fusion Materials Irradiation Facility (IFMIF) aiming at material tests for fusion power plants, the construction of the Linear IFMIF Prototype Accelerator (LIPAc) has been conducted at Rokkasho, Japan under the Broader Approach Agreement. The commissioning of LIPAc has been progressing significantly. The world most powerful RFQ successfully accelerated proton beam of 58 mA, and an important project milestone of the acceleration of deuteron beam to 5 MeV with the beam current of 125 mA in pulse mode was successfully achieved. The result proves the validity of the present RFQ design. The adjustment and tuning of the RF power system and the injector for enabling an operation at maximum performances played an important role in achieving this result. For the next step, the preparation of the high duty cycle operation of RFQ is underway. The installation of the HEBT (High Energy Beam Transport line) and the beam dump accepting 1 MW, CW beam, has been completed and a new beam transport line is under manufacturing. Also the assembly of the Superconducting RF (SRF) linac to accelerate the beam up to 9 MeV started in a clean room in Rokkasho.

Design and configurations for the Shielding of the Beam Dump of IFMIF DONES

IFMIF-DONES (International Fusion Materials Irradiation Facility – DEMO Oriented Neutron Source) is currently being developed in the frame of the EUROfusion Early Neutron Source work package (WPENS). It will be an installation for fusion material testing, that will generate a flux of neutrons of 1018 m−2s−1 with a broad peak at 14 MeV by Li(d,xn) nuclear reactions thanks to a deuteron beam colliding on a liquid Li flow.The accelerator system is in charge of providing such high energy deuterons in order to produce the neutron flux expected. The objective of the Beam Dump, part of the High Energy Beam Transport Line (HEBT), is to stop the pulsed beam at low duty cycle during DONES accelerator commissioning and start-up phases.The present work explains the radiological design of the beam dump shielding and two different configuration approaches for the materialization of the design. The radiological design considers maintenance and operation, and it was done together with the building walls dimensioning so that the combined radiation attenuation by the local shield and the building leads to dose rates in the different rooms that satisfy the requirements. Activation of the materials in the HEBT line, originated by the leakage of neutrons through the beam dump entrance is evaluated and an ad-hoc solution is proposed for its minimization. Regarding the mechanical design, in the first configuration, the shielding is split into two halves horizontally, the upper-half requiring external lifting capabilities for its commission and maintenance. The second approach consists in a vertical splitting into two halves, which are self-moveable, avoiding the needs of external lifting capabilities for the remote handling of the shielding.

Magnetic Design and Fabrication of Warm-Iron Normal-Conducting Quadrupole Magnets for ReA3 HEBT Line at NSCL

The ReA3 reaccelerator facility at the National Superconducting Cyclotron Laboratory (NSCL), Michigan State University (MSU), East Lansing, MI, USA, provides unique access to high-quality beams of a wide variety of isotopes for scientific research. The high-energy beam transport (HEBT) line from the ReA3 superconducting linear accelerator to the three experimental end stations consists of several iron-dominated normal-conducting quadrupole magnets, dipole magnets, and also combined-function horizontal and vertical corrector magnets. This article focuses on the design and fabrication of a new type of normal-conducting quadrupole magnet with cylindrical split yoke structure and standard quadrupole coils. Electromagnetic simulation results demonstrate that the magnet design fulfills the performance requirements for the ReA3 HEBT beamline. We present the coil fabrication and mechanical assembly details of the magnet. Our analysis results show that the hydraulic requirements for the coils are met.

Beam Dynamics And Diagnostics For The High Energy Beam Transport Line of Minerva Project At Sck-Cen

MYRRHA will be a research infrastructure highlighted by the first prototype of a sub-critical nuclear reactor driven by a 600 MeV particle accelerator (ADS). This project aims at exploring the transmutation of long-lived nuclear wastes. A first phase is planned to validate the reliability of a 100 MeV/4 mA Protons LINAC carrying the beam toward an ISOL facility, prefiguring the real MYRRHA demonstrator at 600 MeV [1]. This project is called MINERVA [2]. This paper presents the status of the beam dynamic studies for the high energy beam transport lines at 100 MeV. In agreement with the project requirements, we describe the specificities of these beam lines for which it is needed to implement a fast kicker-septum. This system will separate the beam between two main lines: toward the beam dump or the ISOL facility [3]. We also describe the studies on the Beam Position Monitor (BPM) selected for MYRRHA. Part of this work was support by the MYRTE project of the European Union [4].

Performance validation of the iron-dominated, normal-conducting 45°dipole magnets in the ReA3 HEBT line at NSCL, MSU

Abstract The Re-Accelerator (ReA3) facility at the National Superconducting Cyclotron Laboratory (NSCL) at Michigan State University (MSU) delivers rare isotope and stable beams ranging from 0.3 MeV/u to 6 MeV/u to experimental end stations. The High Energy Beam Transport (HEBT) line into the ReA3 experimental hall houses several quadrupole magnets, dipole magnets, and combined function horizontal and vertical corrector magnets. All of these are iron-dominated, resistive type magnets. This paper describes the magnetic performance of 45°dipole magnets installed in both the vertical and horizontal section of the ReA3 beamline. The computed field map and the derived data provide a reference for the operational setting of the magnet and input for the beam optics study. The field measured by both Hall and NMR probes agrees well with the calculations suggesting that the magnet performance meets the design specification.

Alignment technology of heavy ion medical machine

Heavy ion medical machine (HIMM) is built by the Institute of Modern Physics, Chinese Academy of Sciences, with a high-energy beam transport line with a height of 18 m, and its complex space mounting structure increases the difficulty of installation and alignment. The aim of this paper is to provide methods to install all accelerator components efficiently and to ensure that the alignment accuracies of all installed components are within the designed values. We accomplished the fiducialization and pre-alignment of complex modules by combining the laser tracker and the alignment telescope. By analyzing various elements that affect the accuracy of alignment, a method of alignment for high-energy beam transport line was proposed based on high-precision three-dimensional control network. All components have been installed and aligned in a short time, alignment position accuracy of magnets is less than 0.1 mm, and the treatment components alignment accuracy is no more than 0.4 mm. On the basis of error analysis, all alignment results are better than the required precisions, and all of these guaranteed the successful operation of HIMM.

Radio frequency measurement and tuning of a 13 MeV Alvarez-type drift tube linac for a compact pulsed hadron source.

This paper describes the radio frequency (RF) measurement and tuning result of a 13 MeV Alvarez-type drift tube linac (DTL) for a compact pulsed hadron source (CPHS) at Tsinghua University. The design, machining, assembly, and alignment of the DTL are presented for integrity. The CPHS project consists of a high-current proton linac (13 MeV, 16 kW, peak current of 50 mA, 0.5 ms pulse width at 50 Hz), a neutron target station, a small-angle neutron scattering instrument, and a neutron imaging/radiology station. The linac contains an electron cyclotron resonance ion source, a low energy beam transport line, a four-vane radio frequency quadrupole (RFQ) accelerator, an Alvarez-type DTL, a high energy beam transport line, and a RF power supply and distributor. Construction on the CPHS started in June 2009, and the CPHS has provided 2000 h since 2013 to users with the neutrons produced by the 3 MeV proton beam from the radio frequency quadrupole bombarding on the beryllium target as an achievement of its mid-term objective. Presently, the tuning of the assembled DTL cavity has been completed successfully. The 4.3-m-long DTL consists of 40 accelerating cells, among which 39 full-length drift tubes (DTs) are suspended inside the cavity, and two half-length DTs are mounted inside the two end flanges of the cavity. Each DT contains a permanent magnet quadrupole. Thirteen post couplers and nine tuners are available for the tuning of the field. The relative error of the field after tuning is within ±1.6%, with a tilt sensitivity within ±33%/MHz in all cells. The beam energy will reach its designed value of 13 MeV after the DTL is installed in the beam line downstream the 3 MeV RFQ accelerator.

Emittance matching of a slow extracted beam for a rotating gantry

The introduction of a heavy-ion rotating gantry is in progress at the Heavy Ion Medical Accelerator in Chiba (HIMAC) for realizing high-precision cancer therapy using heavy ions. A scanning irradiation method will be applied to this gantry course with 48–430MeV/u beam energy. In the rotating gantry, the horizontal and vertical beam parameters are coupled by its rotation. To maintain a circular spot shape at the isocenter irrespective of the gantry angle, achieving symmetric phase space distribution of the horizontal and vertical beam at the entrance of the rotating gantry is necessary. Therefore, compensating the horizontal and vertical emittance is necessary. We consider using a thin scatterer method to compensate the emittance. After considering the optical design for emittance matching, the scatterer device is located in the high-energy beam transport line. In the beam commissioning, we confirm that the symmetrical spot shape is obtained at the isocenter without depending on the gantry angle.