Etude d’un module accélérateur supraconducteur et de ses systèmes de régulation pour le projet MYRRHA

The MYRRHA ( Multi-purpose hYbrid Research Reactor for High-tech Applications ) project aims at constructing an accelerator driven system (ADS) demonstrator (50 à 100 MWth) to explore the feasibility of nuclear waste transmutation. Such a subcritical reactor requires an extremely reliable accelerator which delivers a CW high power protons beam (600 MeV, 4 mA). The reference solution for this machine is a superconducting linear accelerator. This thesis presents the work - undertaken at IPN Orsay in October 2008 - on the study of a prototypical superconducting module and the feedback control systems of its cavity for the high energy part of the MYRRHA linac. First, the optimization and the design of 5-cell elliptical cavities (β=0,65), operating at 704.4 MHz, are presented. Then, the experimental work focuses on a reliability oriented study of the “cryomodule” which hold a prototypical 5-cell cavity (β=0,47). In this study, the dynamic behavior of the fast tuning system of the cavity was measured and qualified. The “field flatness” issue in “low beta” multi-cell cavity was also brought to light. Finally, a fault-tolerance analysis of the linac was carried out. Toward this goal, a model of the cavity, its RF feedback loop system and its tuning system feedback loop was developed. This study enabled to determine the RF power needs, the tuning system requirements and as well as to demonstrate the feasibility of fast fault-recovery scenarios to minimize the number of beam interruptions in the MYRRHA linac

Method Development for Cavity Failure Compensation in a Superconducting Linac

International audienceReliability is a major challenge within the perspective of improving the performances and sustainability of MegaWatt class accelerators. To optimize the operational costs of such accelerators the availability requirements are becoming more and more challenging. These requirements are even more stringent in the case of Accelerator Driven systems (ADS). As an example, for the MYRRHA (Multipurpose Hybrid Research Reactor for High-tech Applications) ADS demonstrator, the actual availability limit is set to a maximum of 10 beam interruptions (longer than 3 seconds) over a 3-month operating cycle. For this purpose, the accelerator design is based on a redundant and fault-tolerant scheme to enable rapid mitigation of a cavity failure. The adopted strategy is to apply for local compensation: a failed cavity is compensated by several neighboring cavities. Beam dynamics studies and method developments to apply such a failure compensation scheme are here reviewed. First simulation results for superconducting linac retuning and potential future improvements will be discussed

MYRRHA Superconducting linac & Fault Tolerance Concept

presentation at the virtual conference LINAC20International audienc

The MYRRHA Superconducting linac - Fault-tolerant design and developments

presentation at Fourth International Workshop on Technology and Components for Accelerator Driven Systems (TCADS-4)International audienc

Etude d’un module accélérateur supraconducteur et de ses systèmes de régulation pour le projet MYRRHA

The MYRRHA ( Multi-purpose hYbrid Research Reactor for High-tech Applications ) project aims at constructing an accelerator driven system (ADS) demonstrator (50 à 100 MWth) to explore the feasibility of nuclear waste transmutation. Such a subcritical reactor requires an extremely reliable accelerator which delivers a CW high power protons beam (600 MeV, 4 mA). The reference solution for this machine is a superconducting linear accelerator. This thesis presents the work - undertaken at IPN Orsay in October 2008 - on the study of a prototypical superconducting module and the feedback control systems of its cavity for the high energy part of the MYRRHA linac. First, the optimization and the design of 5-cell elliptical cavities (β=0,65), operating at 704.4 MHz, are presented. Then, the experimental work focuses on a reliability oriented study of the “cryomodule” which hold a prototypical 5-cell cavity (β=0,47). In this study, the dynamic behavior of the fast tuning system of the cavity was measured and qualified. The “field flatness” issue in “low beta” multi-cell cavity was also brought to light. Finally, a fault-tolerance analysis of the linac was carried out. Toward this goal, a model of the cavity, its RF feedback loop system and its tuning system feedback loop was developed. This study enabled to determine the RF power needs, the tuning system requirements and as well as to demonstrate the feasibility of fast fault-recovery scenarios to minimize the number of beam interruptions in the MYRRHA linac.Afin d'étudier la faisabilité de la technologie ADS (« Accelerator Driven System ») pour la transmutation des déchets hautement radiotoxiques le projet MYRRHA (« Multi-purpose hYbrid Research Reactor for High-tech Applications ») a pour objectif la construction d'un démonstrateur de réacteur hybride (50 à 100 MWth). Pour cela le réacteur sous-critique nécessite un accélérateur de forte puissance délivrant un faisceau continu de protons (600 MeV, 4mA), avec une exigence de fiabilité très élevée. La solution de référence retenue pour cette machine est un accélérateur linéaire supraconducteur. Ce mémoire de thèse décrit le travail de recherche - entrepris depuis octobre 2008 à l'IPN d'Orsay - portant sur la conception et la mise au point d'un module supraconducteur et des systèmes de régulation associés à sa cavité accélératrice, pour la partie haute énergie de l’accélérateur. Dans un premier temps, le design et l’optimisation de cavités accélératrices 5-cellules (β=0,65), fonctionnant à la fréquence de 704,4 MHz, sont présentés. Ensuite, la partie expérimentale se concentre sur l’étude de fiabilité du « cryomodule » prototype accueillant une cavité elliptique 5-cellules (β=0,47). Au cours de cette étude on s’est notamment attaché à mesurer et à caractériser le comportement dynamique du système d’accord. Les problématiques de maintient du « plat de champ » dans les cavités multi-cellules « bas béta » ont aussi été mises en évidence. Enfin, une analyse sur la tolérance aux pannes de l’accélérateur linéaire a été menée. Dans ce but, une modélisation de la cavité, de sa boucle de régulation RF (radiofréquence) et de la boucle de contrôle de son système d'accord, a été développée afin d'étudier les comportements transitoires de cet ensemble. Cette étude a permis de chiffrer les besoins en puissance RF et les performances requises du système d’accord et de démontrer la faisabilité d’un réglage rapides des cavités supraconductrices afin de minimiser le nombre d’arrêts faisceau dans le linac de MYRRHA

The MYRRHA Superconducting linac - Fault-tolerant design and developments

presentation at Fourth International Workshop on Technology and Components for Accelerator Driven Systems (TCADS-4)International audienc

Study of an accelerating superconducting module and its feedback loop systems for the MYRRHA project

Afin d'étudier la faisabilité de la technologie ADS (« Accelerator Driven System ») pour la transmutation des déchets hautement radiotoxiques le projet MYRRHA (« Multi-purpose hYbrid Research Reactor for High-tech Applications ») a pour objectif la construction d'un démonstrateur de réacteur hybride (50 à 100 MWth). Pour cela le réacteur sous-critique nécessite un accélérateur de forte puissance délivrant un faisceau continu de protons (600 MeV, 4mA), avec une exigence de fiabilité très élevée. La solution de référence retenue pour cette machine est un accélérateur linéaire supraconducteur. Ce mémoire de thèse décrit le travail de recherche - entrepris depuis octobre 2008 à l'IPN d'Orsay - portant sur la conception et la mise au point d'un module supraconducteur et des systèmes de régulation associés à sa cavité accélératrice, pour la partie haute énergie de l’accélérateur. Dans un premier temps, le design et l’optimisation de cavités accélératrices 5-cellules (β=0,65), fonctionnant à la fréquence de 704,4 MHz, sont présentés. Ensuite, la partie expérimentale se concentre sur l’étude de fiabilité du « cryomodule » prototype accueillant une cavité elliptique 5-cellules (β=0,47). Au cours de cette étude on s’est notamment attaché à mesurer et à caractériser le comportement dynamique du système d’accord. Les problématiques de maintient du « plat de champ » dans les cavités multi-cellules « bas béta » ont aussi été mises en évidence. Enfin, une analyse sur la tolérance aux pannes de l’accélérateur linéaire a été menée. Dans ce but, une modélisation de la cavité, de sa boucle de régulation RF (radiofréquence) et de la boucle de contrôle de son système d'accord, a été développée afin d'étudier les comportements transitoires de cet ensemble. Cette étude a permis de chiffrer les besoins en puissance RF et les performances requises du système d’accord et de démontrer la faisabilité d’un réglage rapides des cavités supraconductrices afin de minimiser le nombre d’arrêts faisceau dans le linac de MYRRHA.The MYRRHA ( Multi-purpose hYbrid Research Reactor for High-tech Applications ) project aims at constructing an accelerator driven system (ADS) demonstrator (50 à 100 MWth) to explore the feasibility of nuclear waste transmutation. Such a subcritical reactor requires an extremely reliable accelerator which delivers a CW high power protons beam (600 MeV, 4 mA). The reference solution for this machine is a superconducting linear accelerator. This thesis presents the work - undertaken at IPN Orsay in October 2008 - on the study of a prototypical superconducting module and the feedback control systems of its cavity for the high energy part of the MYRRHA linac. First, the optimization and the design of 5-cell elliptical cavities (β=0,65), operating at 704.4 MHz, are presented. Then, the experimental work focuses on a reliability oriented study of the “cryomodule” which hold a prototypical 5-cell cavity (β=0,47). In this study, the dynamic behavior of the fast tuning system of the cavity was measured and qualified. The “field flatness” issue in “low beta” multi-cell cavity was also brought to light. Finally, a fault-tolerance analysis of the linac was carried out. Toward this goal, a model of the cavity, its RF feedback loop system and its tuning system feedback loop was developed. This study enabled to determine the RF power needs, the tuning system requirements and as well as to demonstrate the feasibility of fast fault-recovery scenarios to minimize the number of beam interruptions in the MYRRHA linac

Cavity Failure Compensation Strategies in Superconducting Linacs

International audienceRF cavities in linear accelerators are subject to failure, preventing the beam from reaching it’s nominal energy. This is particularly problematic for Accelerator Driven Systems (ADS), where the thermal fluctuations of the spallation target must be avoided and every fault shall be rapidly compensated for. In this study we present LightWin. This tool under development aims to create a database of the possible cavity failures and their associated compensation settings for a given accelerator. We apply it on the MYRRHA ADS, with a scenario including various faults distributed along the accelerator, and compare the settings found by LightWin to those found by the code TraceWin. We show that both tools find different compensation settings. We also outline the limitations of LightWin and explain the upcoming improvements

Wire Scanner for High Intensity Ion Beam

International audienceThe goal of the project is to develop a Wire-Scanner compatible with low energy - high intensity ion beams and adaptable to various beam chamber diameters. The purpose is to obtain the 2D beam profile by passing measurement wires through the beam. Thanks to a high speed passage of measurement wires, it allows to avoid "disrupting" the beam passage, and can be considered as a non-destructive diagnosis. Wires heating and measuring issues have been solved by using tungsten wires kept in tension by a mechanical system. All driving and signal measurements are performed by a PXI based system. The synchronization of the measurements is guaranteed by an analog input board recovering the wires current and the translator position, the latter being carried out by a laser sensor. Besides this technological aspect, an optimization algorithm for beam profile reconstruction from measured data under Gaussian hypothesis has been developed. The standalone system and first experimental results are presented

Summary of the Working Group B

International audienceSummary of the Working Group on Beam Dynamics in Linacs