ANL, Argonne, USA
The first pair of superconducting niobium half-wave resonators operating at 162.5 MHz for the FNAL PIP-II project are complete and this poster reports the cold test results. These cavities are optimized to accelerate protons/H− from 2 to 10 MeV and build upon optimized electromagnetic designs and processing techniques developed at Argonne for the Intensity Upgrade of the ATLAS superconducting heavy ion accelerator.
ANL, Argonne, USA
Stony Brook University, Stony Brook, USA
BNL, Upton, Long Island, New York, USA
SBU, Stony Brook, New York, USA
The electron-ion collider project (eRHIC) at Brookhaven National Laboratory requires a 50 mA 12 MeV electron injector linac for eRHIC main linac and an SRF electron gun for a Coherent electron Cooling (CeC) linac. The necessity to deal with long electron bunches required for both the eRHIC injector and the coherent electron cooler sets the frequency requirement of 84.5 MHz. Quarter wave resonator is a perfect choice for this frequency because of its dimensions, RF parameters and good experience with manufacturing and using them at ANL. Here we present the design and optimization of an 84.5 MHz 2.5 MV superconducting quarter-wave cavity suitable for both machines. One such QWR will be used as a bunching cavity in the injector linac, the other one as the photoemission electron source for the CeC linac. In addition to the optimization of the QWR electromagnetic design we will discuss the tuner design, approaches to cavity fabrication and processing.
ANL, Argonne, USA
A compact linac design has been developed for an Accelerator Driven System (ADS). The linac is under 150 meters in length and comprises a radio-frequency quadrupole (RFQ) and 20 superconducting modules. Three types of half-wave cavities and two types of elliptical cavities have been designed and optimized for high performance at frequencies of 162.5, 325 and 650 MHz. The lattice is being designed and optimized for operation with a peak power of 25 MW for a 25 mA – 1 GeV proton beam. The cavities RF design as well as the linac lattice will be presented along with end-to-end beam dynamics simulations for beam currents ranging from 0 to 25 mA.
Fermilab, Batavia, Illinois, USA
ANL, Argonne, Illinois, USA
ANL, Argonne, USA
The Argonne National Laboratory ATLAS accelerator’s Intensity and Efficiency Upgrade project has been successfully finished [1]. This upgrade substantially increases beam currents for experimenters working with the existing stable and in-flight rare isotope beams and for the neutron rich beams from the Californium Rare Isotope Breeder upgrade. A major portion of this project involved the replacement of three existing cryomodules, containing 18 superconducting (SC) accelerator cavities and 9 superconducting solenoids, with a single cryomodule containing 7 SC 72.75 MHz accelerator cavities optimized for ion velocities of 7.7% the speed of light and 4 SC solenoids all operating at 4.5 K. This paper reports the measured thermal load to the 4 K and 80 K coolant streams and compares these results to the pre-upgrade cryogenic system.
ANL, Argonne, USA
A cryomodule of seven 72 MHz SC quarter-wave cavities optimized for ions with v/c=0.077 has been commissioned in the ATLAS heavy-ion accelerator at Argonne. ATLAS has a new capability for increased beam currents with low beam losses for nuclear physics experiments using stable or rare isotope beams or neutron rich beams from the Californium Rare Isotope Breeder. The main goal for the cryomodule, to provide an accelerating voltage of 17.5 MV (2.5 MV/cavity), with no detectable beam losses has been met within the first month of commissioning. Thus far, cavities and primary subsystems including high-power couplers and pneumatic tuners are operating as designed with full availability. For present levels there is practically no field emission (EPEAK=40 MV/m) and RF losses of ~5 Watts/cavity are only half of that planned. Cavity fields will continue to be gradually increased, with the limits due to cavity quench measured at VACC=3.75 MV. Due to a combination of rf design and cavity processing, effective voltages are now 2 ½ times those for any other operational cavities for this v/c. We report here on the recent online test results and technical features of the present design.
ANL, Argonne, Illinois, USA
The superconducting cavities and, especially, the magnets in high intensity ion linacs need to be aligned to the beam with typical transverse tolerances of 0.25 mm and 0.1 degrees at temperatures of 1.8 – 4.5 K. This is necessary to limit the emittance growth and minimize the beam losses. A new cryomodule with 7 superconducting quarter-wave resonators and 4 superconducting solenoids has been installed and is now operated at the Argonne Tandem Linear Accelerator System (ATLAS). We developed the techniques necessary to assemble the superconducting components in this cryomodule at room temperature so that they are aligned to the beam axis at 4.5 K. We achieved transverse alignment tolerances of <0.2 mm RMS. In this paper, we will present the details of the alignment hardware, procedures and results.
ANL, Argonne, USA
An in-flight radioactive beam separator, named AIRIS, is being designed to enhance the radioactive beam capabilities of the ATLAS facility at Argonne. In order to serve all the experimental areas while maintaining the stable beam capabilities, the separator design is of broadband type. This design allows the selected radioactive beam to come back on the ATLAS beam line while stable beams continue on the same straight line with the separator turned off. The separation is performed in two steps, the first is magnetic in a chicane made of four magnets and four multipoles, while the second uses an rf sweeper taking advantage of the time separation between the beam of interest and potential contaminants including the primary beam tail. We will report on the progress of the AIRIS design effort with special emphasis on the performance of the rf sweeper.
ANL, Argonne, USA
Illinois Institute of Technology, Chicago, Illlinois, USA
The ANL Physics Division has completed a major upgrade of the ATLAS National User Facility by successfully installing a new RFQ and cryomodule. The new normal conducting CW RFQ capable of providing 295 keV/u beams of any ion with m/q ≤7 from protons to uranium was fully integrated into ATLAS and has been in routine operation for more than a year. The RFQ doubled the efficiency of beam delivery to targets and opened the possibility to accelerate much higher intensity beams. Recently, the new cryomodule containing 7 high-performance 72.75 MHz superconducting quarter-wave resonators and 4 superconducting solenoids was successfully commissioned with beam. New design and fabrication techniques for these resonators resulted in record high voltages which were achieved during the beam commissioning. The new cryomodule provides 17.5 MV accelerating voltage which will be gradually raised by increasing the input RF power and improving LLRF system. The new cryomodule, which replaced 3 old cryomodules that used split-ring cavities, is also essential for high intensity stable beams. Results of beam commissioning and operation of ATLAS with the new RFQ and cryomodule will be presented.
ANL, Argonne, USA
The proposed eXtreme MATerial (XMAT) research facility at ANL’s Advanced Photon Source (APS) combines medium-energy heavy-ion accelerator capability with the high-energy X-ray analysis to enable rapid in situ mesoscale bulk analysis of ion radiation damage in advanced materials and nuclear fuels. The XMAT facility requires CW heavy ion accelerator with adjustable beam energy in the range of 300 keV/u to 1.25 MeV/u. Such an accelerator has been developed and based on ECR, normal conducting RFQ and multi-gap quarter wave resonators (QWR) operating at 60 MHz. This talk will present complete 3D beam dynamics studies and multi-physics design of both RFQ and QWRs. The design includes a beam transport system capable to focus ions into 20-micron diameter spot on the target.