SRF Linac for Future Extension of the Pefp

2010

A superconducting RF cavity with a geometrical beta of 0.42 and a resonant frequency of 700 MHz has been under investigation for an extension program of Proton Engineering Frontier Project (PEFP) to accelerate the proton beam above 100 MeV. We developed and tested a two-cell prototype in order to confirm the fabrication procedure and check the RF and mechanical properties of such a low-beta elliptical cavity. The prototype has been fabricated with high RRR niobium sheets (RRR > 250). Double-ring structure was adopted to reduce the Lorentz force detuning effect. For the vertical test of the prototype cavity, a cryostat was designed and fabricated. Operating temperature is 4.2 K; therefore, pumping to reduce the pressure is not required. We applied 40 layers of superinsulation around the helium vessel in addition to the vacuum insulation between the helium vessel and outer chamber. The status of the prototype development and RF test results will be presented in this paper. TWO-CELL...

2010

A superconducting RF cavity with a geometrical beta of 0.42 and a resonant frequency of 700 MHz has been under consideration for an extension program of Proton Engineering Frontier Project (PEFP) to accelerate the proton beam above 100 MeV. A five-cell prototype was fabricated and tested to confirm the fabrication procedure and to check the RF and mechanical properties. High RRR niobium sheets (RRR > 250) were used for the cavity material, whereas reactor grade niobium and NbTi were used for the beam pipe region and the flange, respectively. Double-ring stiffening structure was adopted to reduce the Lorentz force detuning effect. For the vertical test of the prototype cavity, a cryostat with operating temperature of 4.2 K was designed and fabricated. The cryostat was thermally insulated with 40 layers of MLI and the vacuum jacket and equipped with temperature monitors and liquid level sensors. The RF system for driving the cavity is based on PLL to track the resonance condition. ...

Proceedings of International Conference on Particle Accelerators

Physical Review Special Topics - Accelerators and Beams, 2009

The construction of a 4GeV Superconducting Proton Linac (the SPL) is now part of the Long Term Plan of CERN, and the construction of Linac4, its low-energy front end, has begun. For mid-2011 the existing conceptual design of the SPL has to be refined and transformed into a project proposal. As a first step, basic parameters like RF frequency, accelerating gradient and operating temperature of the superconducting cavities have been re-assessed, taking into account the experience accumulated in the world during the recent years, especially for the SNS and the ILC projects. The conclusions confirm the validity of the initial choices, namely the RF frequency of 704.4MHz and the cooling temperature of ≈ 2K. However the assumed gradients are estimated as optimistic: additional tests are necessary during the coming years to properly define the values to be used in the SPL design. This analysis is documented and its results are explained in this report.

these Proc

The construction of a Superconducting Proton Linac is planned at CERN during the next decade. It is foreseen to be constructed in two stages: a low duty cycle, low-power linac (LPSPL) as an injector for a new 50 GeV synchrotron (PS2) replacing the present PS, which could be upgraded to a high-duty cycle, high-power linac (HPSPL), for the needs of future facility(ies) requiring a multi-MW beam power. In this paper we present the criteria which were used to choose the frequency, gradient, and cryogenic temperature of the SPL. Since these questions are common to other proposed high-power proton linacs, they may also be of use for other projects with similar specifications. The various design options are discussed as well as their impact on beam dynamics, cavity performance, power consumption, cryogenics, and overall efficiency.

2005

A superconducting proton linac (SPL) is considered since a few years as a very interesting accelerator for the future of CERN. This device is planned to serve at the same time as a proton driver for EURISOL, for future neutrino experiments (beta beams, super beams, neutrino factory) and as injector for the CERN accelerator complex. Its parameters have recently been revised, taking into account the evolution of the physics requests and the latest developments in superconducting rf. This work will be summarized in a revised conceptual design report (CDR2) to be published by the end of 2005. This paper highlights the most important changes and the foreseen staged approach towards the SPL. Abstract A superconducting proton linac (SPL) is considered since a few years as a very interesting accelerator for the future of CERN. This device is planned to serve at the same time as a proton driver for EURISOL, for future neutrino experiments (beta beams, super beams, neutrino factory) and as injector for the CERN accelerator complex. Its parameters have recently been revised, taking into account the evolution of the physics requests and the latest developments in superconducting rf. This work will be summarized in a revised conceptual design report (CDR2) to be published by the end of 2005. This paper highlights the most important changes and the foreseen staged approach towards the SPL.

Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 1989

A series of superconducting structures for the acceleration of high-current ion beams is being developed, and two prototype Nb cavities are under construction. These cavities operate in a frequency-velocity range which, for superconducting structures, has been little explored: frequencies of 0.4 GHz to more than 1 GHz, and velocities of 0.1~ to 0.5~. Issues discussed include: need for strong beam loading ( -104), need for strong focusing elements located close to the cavities, minimization of beam impingement and beam instabilities.

Proceedings of the 2005 Particle Accelerator Conference

A Superconducting Linac is being installed as a booster for the 15 UD Pelletron accelerator at Nuclear Science Centre (NSC). The accelerating structure for this linac is a Nb QWR cavity, designed and fabricated as a joint collaboration between NSC and ANL, USA. Initial cavities required for the first linac module were fabricated at ANL. For fabrication of cavities required for future modules a Superconducting Resonator Fabrication Facility has been set up at NSC. Three quarter wave resonator (QWR) cavities have been fabricated using the in-house facility. This facility has been used for repairs on the resonators which sprung leaks. Fabrication of fifteen resonators for the second and third linac modules is under progress. Eight resonators along with a superconducting solenoid has been installed in the first linac cryostat and tested for energy gain with a pulsed beam of 90 MeV Si from the Pelletron. Acceleration of the ions to 96 MeV was measured downstream and beam transmission through the linac was measured to be 1 00%.

Proceedings of the 2005 Particle Accelerator Conference, 2005

As part of its efforts for the SNS construction project, Jefferson Lab has produced 23 cryomodules for the superconducting linac. These modules contained 81 industrially produced multicell Nb accelerating cavities. Each of these cavities was individually tested before assembly into a cryomodule to verify that they achieved the required performance. This ensemble of cavities represents the 3rd largest set of production superconducting cavities fabricated and tested to date. The timely qualification testing of such a collection of cavities offers both challenges and opportunities. Their performance can be characterized by achieved gradient at the required Qo, achieved peak surface field, onset of field emission, and observations of multipacting. Possible correlations between cavity performance and process parameters, only really meaningful in the framework of a large scale production effort, will also be presented. In light of the potential adoption of these cavities for projects such as the Rare Isotope Accelerator or Fermilab Proton Driver, such an analysis is crucial to their success.

2014

The Superconducting Proton Linac (SPL) is an R&D effort conducted by CERN in partnership with other international laboratories, aimed at developing key technologies for the construction of a multimegawatt proton linac based on state-of-the-art SRF technology. Such an accelerator could serve as a driver in new physics facilities for neutrinos and/or radioactive ion beams [1]. Amongst the main objectives of this effort, are the development of 704 MHz bulk niobium beta=1 elliptical cavities (operating at 2 K and providing an accelerating gradient of 25 MV/m) and the test of a string of cavities integrated in a machine-type cryo-module. In an initial phase, only four out of the eight cavities of the SPL cryo-module will be tested in a half-length cryo-module developed for this purpose, which nonetheless preserves the main features of the full size module. This paper presents the final design of the cryo-module and the status of the construction of the main cryostat parts. Preliminary plans for the assembly and testing of the cryo-module at CERN are also presented.