SRF2013 - List of Authors (Molloy, S.)

Paper

Title

Page

The ESS Superconducting Linear Accelerator

77

C. Darve, M. Eshraqi, M. Lindroos, D.P. McGinnis, S. Molloy
ESS, Lund, Sweden
P. Bosland
CEA/IRFU, Gif-sur-Yvette, France
S. Bousson
IPN, Orsay, France

The European Spallation Source (ESS) is one of Europe's largest planned research infrastructure. The collaborative project is funded by a collaboration of 17 European countries and is under design and construction in Lund, Sweden. The ESS will bring new insights to the grand challenges of science and innovation in fields as diverse as material and life sciences, energy, environmental technology, cultural heritage solid-state and fundamental physics. A 5 MW, long pulse proton accelerator is used to reach this goal. The pulsed length is 2.86 ms, the repetition frequency is 14 Hz (4 % duty cycle). The choice of SRF technology is a key element in the development of the ESS linear accelerator(linac). The superconducting linac is composed of one section of spoke cavity cryomodule (352 MHz) and two sections of elliptical cavity cryomodules (704 MHz). These cryomodules contain Niobium SRF cavities operating at 2 K. This paper presents the superconducting linac layout and its lifecycle.

THP048

The Influence of Tuners and Temperature on the Higher Order Mode Spectrum for 1.3 GHz SCRF Cavities

1016

R. Ainsworth
Royal Holloway, University of London, Surrey, United Kingdom
N. Baboi, M.K. Grecki, T. Wamsat
DESY, Hamburg, Germany
N. Eddy
Fermilab, Batavia, USA
S. Molloy
ESS, Lund, Sweden
P. Zhang
CERN, Geneva, Switzerland

Higher Order Modes are of concern for superconducting cavities as they can drive instabilities and so are usually damped and monitored. With special dedicated electronics, HOMs can provide information on the position on the beam. It has been proposed that piezo tuners used to keep the cavities operating at 1.3 GHz could alter the HOM spectrum altering the calibration constants used to read out the beam position affecting long term stability of the system. Also, of interest is how the cavity reacts to the slow tuner. Detuning and the retuning the cavity may alter the HOM spectrum. This is of particular interest for future machines not planning to use dedicated HOM damping as the tuning procedure may shift the frequency of HOMs onto dangerous resonances. The effect of temperature on the HOM spectrum is also investigated. An investigation of these effects has been performed at FLASH and the results are presented including numerical simulations used to predict the resulting cavity distortion.

FRIOC01

Design of the 352 MHz, Beta 0.50, Double-Spoke Cavity for ESS

1212

P. Duchesne, S. Bousson, S. Brault, P. Duthil, G. Olry, D. Reynet
IPN, Orsay, France
S. Molloy
ESS, Lund, Sweden

The ESS proton accelerator contains a superconducting sector consisting in three families of superconducting radiofrequency (SRF) bulk niobium cavities, operating at a nominal temperature of 2K: a family of Spoke cavities for the medium energy section followed by two families of elliptical cavities for higher energies. The superconducting Spoke section, having a length of 58.6m, consists of 14 cryomodules, each of them housing two 352.2 MHz β=0.50 Double-Spoke Resonators (DSR). The operating accelerating field is 8MV/m. The choice of the Spoke technology is guided by the high performances of such structures. Benefitting from 10 years of extensive R&D experience carried out at IPNO, the electromagnetic design studies came out with a solution that fulfills requirements of beam dynamics analysis and manufacturing considerations. Pursuing the same objective, the mechanical design of the cavity and its helium vessel were optimized by performing intensive coupled RF-mechanical simulations. We propose to present a review of the RF and mechanical design studies of the Spoke cavity. We will conclude with the integration of the Spoke cavity with its ancillaries inside the cryomodule.

Slides FRIOC01 [6.321 MB]

Paper	Title	Page
MOP004	The ESS Superconducting Linear Accelerator	77
	C. Darve, M. Eshraqi, M. Lindroos, D.P. McGinnis, S. Molloy ESS, Lund, Sweden P. Bosland CEA/IRFU, Gif-sur-Yvette, France S. Bousson IPN, Orsay, France
	The European Spallation Source (ESS) is one of Europe's largest planned research infrastructure. The collaborative project is funded by a collaboration of 17 European countries and is under design and construction in Lund, Sweden. The ESS will bring new insights to the grand challenges of science and innovation in fields as diverse as material and life sciences, energy, environmental technology, cultural heritage solid-state and fundamental physics. A 5 MW, long pulse proton accelerator is used to reach this goal. The pulsed length is 2.86 ms, the repetition frequency is 14 Hz (4 % duty cycle). The choice of SRF technology is a key element in the development of the ESS linear accelerator(linac). The superconducting linac is composed of one section of spoke cavity cryomodule (352 MHz) and two sections of elliptical cavity cryomodules (704 MHz). These cryomodules contain Niobium SRF cavities operating at 2 K. This paper presents the superconducting linac layout and its lifecycle.

THP048	The Influence of Tuners and Temperature on the Higher Order Mode Spectrum for 1.3 GHz SCRF Cavities	1016
	R. Ainsworth Royal Holloway, University of London, Surrey, United Kingdom N. Baboi, M.K. Grecki, T. Wamsat DESY, Hamburg, Germany N. Eddy Fermilab, Batavia, USA S. Molloy ESS, Lund, Sweden P. Zhang CERN, Geneva, Switzerland
	Higher Order Modes are of concern for superconducting cavities as they can drive instabilities and so are usually damped and monitored. With special dedicated electronics, HOMs can provide information on the position on the beam. It has been proposed that piezo tuners used to keep the cavities operating at 1.3 GHz could alter the HOM spectrum altering the calibration constants used to read out the beam position affecting long term stability of the system. Also, of interest is how the cavity reacts to the slow tuner. Detuning and the retuning the cavity may alter the HOM spectrum. This is of particular interest for future machines not planning to use dedicated HOM damping as the tuning procedure may shift the frequency of HOMs onto dangerous resonances. The effect of temperature on the HOM spectrum is also investigated. An investigation of these effects has been performed at FLASH and the results are presented including numerical simulations used to predict the resulting cavity distortion.

FRIOC01	Design of the 352 MHz, Beta 0.50, Double-Spoke Cavity for ESS	1212
	P. Duchesne, S. Bousson, S. Brault, P. Duthil, G. Olry, D. Reynet IPN, Orsay, France S. Molloy ESS, Lund, Sweden
	The ESS proton accelerator contains a superconducting sector consisting in three families of superconducting radiofrequency (SRF) bulk niobium cavities, operating at a nominal temperature of 2K: a family of Spoke cavities for the medium energy section followed by two families of elliptical cavities for higher energies. The superconducting Spoke section, having a length of 58.6m, consists of 14 cryomodules, each of them housing two 352.2 MHz β=0.50 Double-Spoke Resonators (DSR). The operating accelerating field is 8MV/m. The choice of the Spoke technology is guided by the high performances of such structures. Benefitting from 10 years of extensive R&D experience carried out at IPNO, the electromagnetic design studies came out with a solution that fulfills requirements of beam dynamics analysis and manufacturing considerations. Pursuing the same objective, the mechanical design of the cavity and its helium vessel were optimized by performing intensive coupled RF-mechanical simulations. We propose to present a review of the RF and mechanical design studies of the Spoke cavity. We will conclude with the integration of the Spoke cavity with its ancillaries inside the cryomodule.
	Slides FRIOC01 [6.321 MB]