IPAC2011 - List of Authors (Eshraqi, M.)

Paper	Title	Page
WEPS102	Latest News on the Beam Dynamics Design of SPL	2748
	P.A. Posocco, M. Eshraqi, A.M. Lombardi CERN, Geneva, Switzerland
	SPL is a superconducting H− LINAC under study at CERN. The SPL is designed to accelerate the 160 MeV beam of LINAC4 to 5 GeV, and is composed of two fami¬lies of 704.4 MHz elliptical cavities with geometrical betas of 0.65 and 1.0. Two families of cryo-modules are considered: the low-beta cryo-module houses 3 low-beta cavities, whereas the high-beta one houses 8 cavities. The transverse focusing is performed with normal-conducting quadrupoles arranged in 2 different lattices: FD0 at lower and F0D0 at higher energies. The regular lattices are in-terrupted at the transition between low beta and high beta cryo-modules and for extracting medium energy beams at 1.4 and 2.5 GeV, where the change of the transverse lattice is performed. In this paper the latest beam dynamics studies will be presented together with the sensitivity of the SPL performance to RF errors, alignment tolerances and quadrupole high order components.

WEPS059	Layout of the ESS Linac	2631
	H. Danared, M. Eshraqi, W. Hees, A. Jansson, M. Lindroos, S. Peggs, A. Ponton ESS, Lund, Sweden
	The European Spallation Source will use a 2.5 GeV, 50 mA pulsed proton linac to produce an average 5 MW of power on the spallation target. It will consist of normal-conducting part accelerating particles to 50 MeV in an RFQ and a drift-tube linac and a superconducting part with spoke resonators and two families of elliptical cavities. A high-energy beam transport takes the particles through an upgrade section and at least one bend and demagnifies the beam on to the target. The paper will present the current layout of the linac and discuss parameters that define its length from source to target.

WEPS060	Design and Optimization of ESS LINAC	2634
	M. Eshraqi ESS, Lund, Sweden
	The {\sc linac} of the European Spallation Source will accelerate the proton beam to its final energy mainly by using superconducting structures. Therefore choosing the right transition energy between these superconducting structures as well as choosing the cavity length and number of cells which enhances the acceleration is of great importance. Two types of {\sc linac}s will be studied, a {\sc linac} with superconducting quadrupoles and a {\sc linac} with normal conducting, resistive, quadrupoles. The procedure to find the optimized {\sc linac} will be described here.

WEPS061	ESS LINAC, Design and Beam Dynamics	2637
	M. Eshraqi, H. Danared ESS, Lund, Sweden
	The European Spallation Source, {\sc ESS}, will use a linear accelerator delivering a high intensity proton beam with an average beam power of 5~MW to the target station at 2.5~GeV in long pulses of 2~msec. The ESS {\sc Linac} will use two types of superconducting cavities, spoke resonators at low energy and elliptical cavities at high energies. The possibilities to upgrade to a higher power {\sc Linac} at fixed energy are considered. This paper will present a review of the superconducting {\sc Linac} design and the beam dynamics studies.

WEPS062	Design and Beam Dynamics Study of Hybrid ESS LINAC	2640
	M. Eshraqi, H. Danared, W. Hees, A. Jansson ESS, Lund, Sweden
	The European Spallation Source, {\sc ESS}, will use a superconducting linear accelerator delivering high current long pulses with an average beam power of 5~MW to the target station at 2.5~GeV. A new cryomodule architecture is proposed which allows for a transition between cryomodules in the sub-100~K region, this region can work even at room temperature. This new hybrid design will generate a lower heat load with respect to a fully segmented design - while still providing easy access to individual cryomodules for maintenance and repair. This paper will present a review of the {\sc linac} design, beam dynamics studies and a preliminary cryogenic analysis of the transition region.

WEPS063	Compersation of Effect of Malfunctioning Spoke Resonators on Ess Beam Quality	2643
	M. Eshraqi ESS, Lund, Sweden
	The {\sc linac} of the European Spallation Source will accelerate the proton beam to 2.5~GeV, 98\% of this energy is gained using superconducting structures. The superconducting {\sc linac} is composed of two types of cavities, double spoke resonators and five-cell elliptical cavities. The {\sc linac}, which is five times more powerful than the most powerful existing {\sc linac}, and the spoke cavities that have never been used at such a scale make it necessary to study the effect of one or a few spoke resonators not functioning properly and to find a solution where the defect is compensated by retuning of the neighbouring cavities.

WEPS064	Upgrade Strategies for High Power Proton Linacs	2646
	M. Lindroos, H. Danared, M. Eshraqi, D.P. McGinnis, S. Molloy, S. Peggs, K. Rathsman ESS, Lund, Sweden R.D. Duperrier CEA/DSM/IRFU, France J. Galambos ORNL, Oak Ridge, Tennessee, USA
	High power proton linacs are used as drivers for spallation neutron sources, and are proposed as drivers for sub-critical accelerator driven thorium reactors. A linac optimized for a specific average pulse current can be difficult, or inefficient, to operate at higher currents, for example due to mis-matching between the RF coupler and the beam loaded cavity, and due to Higher Order Mode effects. Hardware is in general designed to meet specific engineering values, such as pulse length and repetition rate, that can be costly and difficult to change, for example due to pre-existing space constraints. We review the different upgrade strategies that are available to proton driver designers, both for linacs under design, such as the European Spallation Source (ESS) in Lund, and also for existing linacs, such as the Spallation Neutron Source (SNS) in Oak Ridge. Potential ESS upgrades towards a beam power higher than 5 MW preserve the original time structure, while the SNS upgrade is directed towards the addition of a second target station.

Paper

Title

Page

Latest News on the Beam Dynamics Design of SPL

2748

P.A. Posocco, M. Eshraqi, A.M. Lombardi
CERN, Geneva, Switzerland

SPL is a superconducting H− LINAC under study at CERN. The SPL is designed to accelerate the 160 MeV beam of LINAC4 to 5 GeV, and is composed of two fami¬lies of 704.4 MHz elliptical cavities with geometrical betas of 0.65 and 1.0. Two families of cryo-modules are considered: the low-beta cryo-module houses 3 low-beta cavities, whereas the high-beta one houses 8 cavities. The transverse focusing is performed with normal-conducting quadrupoles arranged in 2 different lattices: FD0 at lower and F0D0 at higher energies. The regular lattices are in-terrupted at the transition between low beta and high beta cryo-modules and for extracting medium energy beams at 1.4 and 2.5 GeV, where the change of the transverse lattice is performed. In this paper the latest beam dynamics studies will be presented together with the sensitivity of the SPL performance to RF errors, alignment tolerances and quadrupole high order components.

WEPS059

Layout of the ESS Linac

2631

H. Danared, M. Eshraqi, W. Hees, A. Jansson, M. Lindroos, S. Peggs, A. Ponton
ESS, Lund, Sweden

The European Spallation Source will use a 2.5 GeV, 50 mA pulsed proton linac to produce an average 5 MW of power on the spallation target. It will consist of normal-conducting part accelerating particles to 50 MeV in an RFQ and a drift-tube linac and a superconducting part with spoke resonators and two families of elliptical cavities. A high-energy beam transport takes the particles through an upgrade section and at least one bend and demagnifies the beam on to the target. The paper will present the current layout of the linac and discuss parameters that define its length from source to target.

WEPS060

Design and Optimization of ESS LINAC

2634

M. Eshraqi
ESS, Lund, Sweden

The {\sc linac} of the European Spallation Source will accelerate the proton beam to its final energy mainly by using superconducting structures. Therefore choosing the right transition energy between these superconducting structures as well as choosing the cavity length and number of cells which enhances the acceleration is of great importance. Two types of {\sc linac}s will be studied, a {\sc linac} with superconducting quadrupoles and a {\sc linac} with normal conducting, resistive, quadrupoles. The procedure to find the optimized {\sc linac} will be described here.

WEPS061

ESS LINAC, Design and Beam Dynamics

2637

M. Eshraqi, H. Danared
ESS, Lund, Sweden

The European Spallation Source, {\sc ESS}, will use a linear accelerator delivering a high intensity proton beam with an average beam power of 5~MW to the target station at 2.5~GeV in long pulses of 2~msec. The ESS {\sc Linac} will use two types of superconducting cavities, spoke resonators at low energy and elliptical cavities at high energies. The possibilities to upgrade to a higher power {\sc Linac} at fixed energy are considered. This paper will present a review of the superconducting {\sc Linac} design and the beam dynamics studies.

WEPS062

Design and Beam Dynamics Study of Hybrid ESS LINAC

2640

M. Eshraqi, H. Danared, W. Hees, A. Jansson
ESS, Lund, Sweden

The European Spallation Source, {\sc ESS}, will use a superconducting linear accelerator delivering high current long pulses with an average beam power of 5~MW to the target station at 2.5~GeV. A new cryomodule architecture is proposed which allows for a transition between cryomodules in the sub-100~K region, this region can work even at room temperature. This new hybrid design will generate a lower heat load with respect to a fully segmented design - while still providing easy access to individual cryomodules for maintenance and repair. This paper will present a review of the {\sc linac} design, beam dynamics studies and a preliminary cryogenic analysis of the transition region.

WEPS063

Compersation of Effect of Malfunctioning Spoke Resonators on Ess Beam Quality

2643

M. Eshraqi
ESS, Lund, Sweden

The {\sc linac} of the European Spallation Source will accelerate the proton beam to 2.5~GeV, 98\% of this energy is gained using superconducting structures. The superconducting {\sc linac} is composed of two types of cavities, double spoke resonators and five-cell elliptical cavities. The {\sc linac}, which is five times more powerful than the most powerful existing {\sc linac}, and the spoke cavities that have never been used at such a scale make it necessary to study the effect of one or a few spoke resonators not functioning properly and to find a solution where the defect is compensated by retuning of the neighbouring cavities.

WEPS064

Upgrade Strategies for High Power Proton Linacs

2646

M. Lindroos, H. Danared, M. Eshraqi, D.P. McGinnis, S. Molloy, S. Peggs, K. Rathsman
ESS, Lund, Sweden
R.D. Duperrier
CEA/DSM/IRFU, France
J. Galambos
ORNL, Oak Ridge, Tennessee, USA

High power proton linacs are used as drivers for spallation neutron sources, and are proposed as drivers for sub-critical accelerator driven thorium reactors. A linac optimized for a specific average pulse current can be difficult, or inefficient, to operate at higher currents, for example due to mis-matching between the RF coupler and the beam loaded cavity, and due to Higher Order Mode effects. Hardware is in general designed to meet specific engineering values, such as pulse length and repetition rate, that can be costly and difficult to change, for example due to pre-existing space constraints. We review the different upgrade strategies that are available to proton driver designers, both for linacs under design, such as the European Spallation Source (ESS) in Lund, and also for existing linacs, such as the Spallation Neutron Source (SNS) in Oak Ridge. Potential ESS upgrades towards a beam power higher than 5 MW preserve the original time structure, while the SNS upgrade is directed towards the addition of a second target station.