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Intense ion beams with small phase space occupation (high brilliance) are mandatory to keep beam losses low in high current injector accelerators like those planned for FAIR. The low energy beam transport from the ion source towards the linac has to keep the emittance growth low and has to support the optimization of the ion source tune. The Frankfurt Neutron Source Facility FRANZ is currently under construction. An intense beam of protons (2 MeV, 200 mA) will be used for neutron production using the Li7(p,n)Be7 reaction for studies of the astrophysical s-process. A collimation channel, which can be adjusted to allow the transport of beams with a certain beam emittance, is an ideal tool to optimize the ion source tune in terms of beam brightness. Therefore a collimation channel in the Low Energy Beam Transport section will be used. Through defined apertures and transversal phase space rotation using focusing solenoids the beam halo as well as unwanted H2+ and H3+ fractions will be cut. Theoretical studies which were carried out so far and a first design of the setup will be presented.
Beam test of the direct plasma injection scheme (DPIS) is carried out successfully for the first time in China, by setting up a comprehensive test and research platform of RFQ and laser ion source. The C6+ beam is accelerated successfully, and the peak beam current reaches more than 6mA which is measured by a Faraday cup of unique structure. The RF power coupled into the RFQ cavity is also examined, and results reveal that it is the RF power of about 195kW that can produce the peak beam current.
A CW RFQ prototype
(2011)
A short RFQ prototype was built for RF-tests of high power RFQ structures. We will study thermal effects and determine critical points of the design. HF-simulations with CST Microwave Studio and measurements were done. The cw-tests with 20 kW/m RF-power and simulations of thermal effects with ALGOR were finished successfully. The optimization of some details of the HF design is on focus now. First results and the status of the project will be presented.
Beam measurements with the new RFQ beam matching section at the Frankfurt Funneling Experiment
(2011)
Funneling is a method to increase low energy beam currents in multiple stages. The Frankfurt Funneling Experiment is a model of such a stage. The experiment is built up of two ion sources with electrostatic lens systems, a Two-Beam-RFQ accelerator, a funneling deflector and a beam diagnostic system. The two beams are bunched and accelerated in a Two-Beam RFQ. A funneling deflector combines the bunches to a common beam axis. A new beam transport system between RFQ accelerator and deflector has been constructed and mounted. With these extended RFQ-electrodes the drift between the Two-Beam-RFQ and the rf-deflector will be minimized and therefore unwanted emittance growth reduced. After first rf measurements current work are beam tests with the improved Two-Beam-RFQ. First results will be presented.
Usually 4-ROD Radio Frequency Quadrupoles (RFQ) are built for frequencies up to 216 MHz. For higher frequencies 4-VANE structures are more common. The advantages of 4-Rod structures, the greater flexibility for tuning and being more comfortable for maintenance, are motivating the development of a 4-Rod RFQ for higher frequencies than 216 MHz. In particular a 325 MHz RFQ with an output energy of 3 MeV is needed for the proton linac for the FAIR project of GSI. This paper reports about the design studies and the latest developments of this RFQ.
For the injector upgrade at FNAL a 4-rod Radio Frequency Quadrupole (RFQ) with a resonance frequency of 200 MHz has been build. With this short structure of only 1.3 m a very compact injector design has been realized. Simulations with CST Microwave Studio® were performed for the design. Their results leading to the RF characterizations of the RFQ and the final RF setup which has been accomplished at IAP of the Goethe-University Frankfurt are presented in this paper.
The LANSCE linear accelerator at Los Alamos National Laboratory provides H− and H+ beams to several user facilities that support Isotope Production, NNSA Stockpile Stewardship, and Basic Energy Science programs. These beams are initially accelerated to 750 keV using Cockcroft-Walton (CW) based injectors that have been in operation for over 37 years. They have failure modes which can result in prolonged operational downtime due to the unavailability of replacement parts. To reduce long-term operational risks and to realize future beam performance goals in support of the Materials Test Station (MTS) and the Matter-Radiation Interactions in Extremes (MaRIE) Facility, plans are underway to develop a Radio-Frequency Quadrupole (RFQ) based front end as a modern injector replacement for the existing CW injectors. Our progress to date will be discussed.
n order to reach the desired intensities of heavy ion beams for the experiments at FAIR, SIS18 and SIS100 have to be operated with intermediate charge states. Operation with intermediate charge state heavy ions at the intensity level of about 1011 ions per cycle has never been demonstrated elsewhere and requires a dedicated upgrade program for SIS18 and a dedicated machine design for SIS100. The specific problems coming along with the intermediate charge state operation in terms of charge exchange processes at collisions with residual gas atoms, pressure bumps by ion induced desorption and corresponding beam loss appears far below the typical space charge limits. Thus, new design concepts and new technical equipment addressing these issues are developed and realized with highest priority. The upgrade program of SIS18 addressing the goal of minimum ionization beam loss and stable residual gas pressure conditions has been defined in 2005. A major part of this upgrade program has been successfully realized, with the result of a world record in accelerated number of intermediate charge state heavy ions.
Accelerator Driven Systems (ADS) are promising tools for the efficient transmutation of nuclear waste products in dedicated industrial installations, called transmuters. The Myrrha project at Mol, Belgium, placed itself on the path towards these applications with a multipurpose and versatile system based on a liquid PbBi (LBE) cooled fast reactor (80 MWth) which may be operated in both critical and subcritical modes. In the latter case the core is fed by spallation neutrons obtained from a 600 MeV proton beam hitting the LBE coolant/target. The accelerator providing this beam is a high intensity CW superconducting linac which is laid out for the highest achievable reliability. The combination of a parallel redundant and of a fault tolerant scheme should allow obtaining an MTBF value in excess of 250 hours that is required for optimal integrity and successful operation of the ADS. Myrrha is expected to be operational in 2023. The forthcoming 4-year period is fully dedicated to R&D activities, and in the field of the accelerator they are strongly focused on the reliability aspects and on the proper shaping of the beam trip spectrum.
Development of fragmented low-Z ion beams for the NA61 fixed-target experiment at the CERN SPS
(2011)
The NA61 experiment, aims to study the properties of the onset of deconfinement at low SPS energies and to find signatures of the critical point of strongly interacting matter. A broad range in T-μB phase diagram will be covered by performing an energy (13A-158A GeV/c) and system size (p+p, Be+Be, Ar+Ca, Xe+La) scan. In a first phase, fragmented ion beams of 7Be or 11C produced as secondaries with the same momentum per nucleon when the incident primary Pb-ion beam hits a thin Be target will be used. The H2 beam line that transports the beam to the experiment acts as a double spectrometer which combined with a new thin target (degrader) where fragments loose energy proportional to the square of their charge allows the separation of the wanted A/Z fragments. Thin scintillators and TOF measurement for the low energy points are used as particle identification devices. In this paper results from the first test of the fragmented ion beam done in 2010 will be presented showing that a pure Be beam can be obtained satisfying the needs of the experiment.