Surface treatments and photodesorption of oxygen free copper used in an accelerator

Koabari, T.; Matumoto, M; Ueda, Shinjiro; Kobayashi, M.; Hori, Yoichiro

doi:10.1109/pac.1993.309829

Cited by 2 publications

(2 citation statements)

References 8 publications

(6 reference statements)

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“…It can also be noticed how most of the RT curves end up converging on the same yield after reaching a dose of 1 × 10 23 ph=m, when the surface is considered already conditioned. This effect is thought to be ascribed to the gas content depletion, the hybridization of the sp 3 surface carbon layer into sp 2 carbon [37] and the increase of the carbon concentration in the irradiated areas [38]. The growth of the sp 2 carbon layer is translated into similar Y ph ultimate values in the different original surfaces.…”

Section: B Primary Photon Stimulated Desorption (Psd)mentioning

confidence: 99%

Beam induced vacuum effects in the future circular hadron collider beam vacuum chamber

Bellafont

Mether

Kersevan

et al. 2020

Phys. Rev. Accel. Beams

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EuroCirCol is a conceptual design study of a post-LHC, Future Circular Hadron Collider (FCC-hh) with 50 TeVof beam energy and 100 km long, which aims to expand the current energy and luminosity frontiers. The vacuum chamber of the FCC-hh will have to cope with unprecedented levels of synchrotron radiation power for proton colliders, dealing simultaneously with a tighter magnet aperture. Considering that the high radiation power and photon flux will release larger amounts of gas into the system, the difficulty to meet the vacuum specifications increases substantially compared with the LHC. This paper presents a study on the beam induced vacuum effects for the FCC-hh novel conditions, the different phenomena which, owing to the presence of the beam, have an impact on the accelerator's vacuum level. It is concluded that thanks to the adopted mitigation measures the proposed vacuum system shall be adequate, allowing us to reach ≤1 × 10 15 H 2 eq =m 3 with baseline beam parameters within the first months of conditioning.

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Section: B Primary Photon Stimulated Desorption (Psd)mentioning

confidence: 99%

Beam induced vacuum effects in the future circular hadron collider beam vacuum chamber

Bellafont

Mether

Kersevan

et al. 2020

Phys. Rev. Accel. Beams

View full text Add to dashboard Cite

show abstract

“…It can also be observed how most of the RT curves end up converging to the same yield after reaching a dose of approximately 1 × 10 23 ph/m, when the surface is traditionally considered conditioned. This is thought to be ascribed to the gas/chemical contaminants depletion and to the growth of a sp 2 carbon layer on the surface [140,141], resulting in a lower photoelectron emission. The growth of the sp 2 carbon layer would be translated into similar values of Y ph at the original surfaces.…”

Section: Primary Photon Stimulated Desorption (Psd)mentioning

confidence: 99%

Study of the beam induced vacuum effects in the cryogenic beam vacuum chamber of the Future Circular Hadron Collider

Bellafont Peralta

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The Future Circular Hadron Collider (FCC-hh) is a proposal for a 100 km long hadron collider conceived as the successor of the Large Hadron Collider (LHC). The FCC-hh is designed to reach 50 TeV of beam energy, greatly surpassing the current energy frontier set by the LHC at 7 TeV. Thus, it is expected to expand the current horizon of understanding of the Standard Model of particle physics. The beam vacuum chamber of the FCC-hh will have to cope with unprecedented levels of synchrotron radiation power for hadron colliders, around 160 times higher than its predecessor, dealing simultaneously with a tighter magnet aperture. Since the higher radiation power will result in a much higher gas load, the difficulty to achieve a good vacuum quality increases considerably compared with the LHC. This thesis presents a study of the so-called beam induced vacuum effects in the FCC-hh, meaning the different phenomena which, due to the presence of the particle beam, have a detrimental impact on the accelerator’s vacuum level. These studied effects are the photon stimulated desorption (PSD), the electron stimulated desorption (ESD) and ion stimulated desorption (ISD). Each effect has been thoroughly studied, calculating analytically and with a series of Monte Carlo simulations the resulting gas density in the chamber for all the common gas species. Finally, the feasibility of the FCC-hh from the vacuum point of view has been assessed. To mitigate the beam induced effects and to improve the vacuum quality in the FCC-hh (essential for a proper machine operation) it was necessary to propose a new beam screen design. The new beam screen features new solutions to mitigate the e- cloud, to handle the synchrotron radiation and a much higher pumping speed, at the expense of a higher manufacturing complexity. A dedicated experimental setup was used by CERN during the design phase to measure the vacuum performance of the developed beam screen prototypes. Finally, the obtained experimental results were compared with the theoretical results to further enhance their validity. It is concluded that thanks to the new beam screen design, the vacuum level in the FCC-hh should be adequate. Using nominal beam parameters, the established FCC-hh vacuum specifications could be met within the first months of conditioning, a reasonable amount of time. El Futuro Colisionador Circular de Hadrones (FCC-hh) es un colisionador de hadrones de 100 km de longitud, propuesto como sucesor del Gran Colisionador de Hadrones (LHC). El FCC-hh está diseñado para alcanzar 50 TeV de energía de haz, superando notoriamente la frontera de energía actual establecida por el LHC, 7 TeV. De esta manera, se espera expandir las fronteras de conocimiento actuales del Modelo Estándar de la física de partículas. La cámara de vacío del haz del FCC-hh deberá soportar niveles de potencia de radiación de sincrotrón sin precedente en los colisionadores de partículas, alrededor de 160 veces más altos que su predecesor, debiendo además de adaptarse a una apertura mucho más reducida. Dado que la alta potencia de radiación resulta en una mayor generación de gas en el sistema, la dificultad de alcanzar un buen nivel de vacío se incrementa considerablemente comparado con el LHC. Esta tesis presenta un estudio de los efectos de vacío inducidos por el haz de partículas en el FCC-hh, esto es, los diferentes fenómenos que, debido a la presencia del haz, tienen un impacto perjudicial en el nivel de vacío del acelerador. Los efectos estudiados son la desorción inducida por fotones (PSD), la desorción inducida por electrones (ESD) y la desorción inducida por iones (ISD). Cada efecto ha sido separadamente estudiado, calculando de manera analítica y mediante simulaciones de Monte Carlo la densidad de gas resultante en la cámara para todas las especies de gas habituales. Por último, la viabilidad del FCC-hh desde el punto de vista del vacío ha sido evaluada. Con el fin de mitigar los efectos de vacío inducidos por el haz y mejorar la calidad del vacío del FCC-hh (esencial para una correcta operación de la máquina) ha sido necesario proponer un nuevo diseño de la pantalla del haz. Este nuevo diseño presenta nuevas soluciones para mitigar la nube de electrones en la cámara, lidiar con la radiación de sincrotrón y una velocidad de bombeo mucho más alta, a expensas de una mayor complejidad en su fabricación. Además, un equipo experimental ha sido usado por el CERN durante para medir el rendimiento en vacío de los prototipos de pantalla de haz construidos. Los resultados experimentales obtenidos han sido finalmente comparados con los resultados teóricos para incrementar su fiabilidad. Se concluye que, gracias al nuevo diseño de la pantalla del haz, el nivel de vacío del FCC-hh será adecuado, alcanzando las especificaciones de vacío establecidas con parámetros de haz nominales dentro de los primeros meses de condicionamiento.

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Surface treatments and photodesorption of oxygen free copper used in an accelerator

Cited by 2 publications

References 8 publications

Beam induced vacuum effects in the future circular hadron collider beam vacuum chamber

Beam induced vacuum effects in the future circular hadron collider beam vacuum chamber

Study of the beam induced vacuum effects in the cryogenic beam vacuum chamber of the Future Circular Hadron Collider

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