| Paper | Title | Page |
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| MOPOR034 | Numerical Space-Charge Compensation Studies and Comparison of Different Models | 674 |
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| The design of many Low-Energy Beam Transport sections relies on the presence of space-charge compensation by particles of opposing charge. To improve understanding of the processes involved in the built-up and steady-state, simulations using the Particle-in-Cell code bender were made. We will present the influence of various system parameters on the results. Furthermore, the electron velocity distribution was found to be approximately thermal. The spatial distribution can then be found by solving the Poisson-Boltzmann equation. Such a model for the electron distribution was implemented in a 2D PIC code and applied to typical beam transport situations. We will present results in comparison to the 3D simulations. | ||
| DOI • | reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOR034 | |
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| MOPOY016 | HSI RFQ Upgrade for the UNILAC Injection to FAIR | 877 |
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| As an injector to the future FAIR facility, the UNILAC accelerator is required to deliver ion beams with high intensities as well as good beam quality. The electrodes of the current HSI RFQ are exhausted and the current RFQ itself is assigned to be one bottle-neck for improving the brilliance performance of the whole linac. Based on the so-called NFSP (New Four-Section Procedure) method, a new RFQ electrode design has been developed and optimized for 20 emA, U4+ beams at the RFQ entrance. Since only the electrodes will be replaced, the RFQ length has been kept unchanged. Even with a lowered inter-vane voltage, the new RFQ design has achieved better beam performance compared to the previous design. This paper will focus on the performed study with respect to beam dynamics. | ||
| DOI • | reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOY016 | |
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| MOPOY017 | Upgrade of the Universal Linear Accelerator UNILAC for FAIR | 880 |
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| In order to meet the requirements on beam parameters for the upcoming FAIR facility at GSI, the injector linac UNILAC will be upgraded. The activities comprise development of the sources for stable provision of intense uranium beams at a repetition rate of 2.7 Hz, a revision of the beam dynamics layout of the 120 keV/u RFQ, the replacement of the matching section to the 1.4 MeV/u pre-stripper DTL, and enhancement of the gaseous stripping section efficiency. This section shall also include a round-to-flat emittance adaptor to prepare the beam for injection into the synchrotron SIS18 which has a flat transverse injection acceptance. Finally, the upgrade includes the complete replacement of the 40 year old 11.4 MeV/u Alvarez-type post-stripper DTL with a new DTL, preferably using Alvarez-type cavities with improved beam focusing features, as well as its rf-power alimentations. | ||
| DOI • | reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOY017 | |
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| MOPOY022 | Further Upgrade Measures at New GSI cw-Linac Demonstrator Setup | 892 |
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| A new continuous wave (cw) linac is required to deliver high intensity heavy ion beams for Super Heavy Element (SHE) future experiments at GSI Darmstadt, Germany. The presented upgrade measures are dedicated to improve the performance of the cw demonstrator setup. The key component is a cryomodule comprising a superconducting (sc) 217 MHz Crossbar-H-mode (CH) cavity surrounded by two sc 9.3T solenoids with compensation coils. The solenoid coil is made of a Nb3Sn wire; and the compensation coils at both ends of the solenoid comprises NbTi wires. The distance between solenoid lense and CH cavity has to be optimized for ideal beam matching as well as for a minimum rest field inside the cavity below the critical magnetic field. The GSI High Charge State (HLI) injector has to deliver a heavy ion beam with an energy of 1.4 MeV/u. Longitudinal matching to the demonstrator is provided by two 108.4 MHz cw room temperature λ/4 re-buncher cavity installed behind the HLI. In this paper electromagnetic simulations of the field optimization for the solenoids and the re-buncher cavities will be presented as well as first beam experiments at the beam transport line to the demonstrator cavity. | ||
| DOI • | reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOY022 | |
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| MOPOY023 | Further Steps Towards the Superconducting CW-LINAC for Heavy Ions at GSI | 896 |
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Funding: Work supported by BMBF contr. No. 05P15RFRBA For future experiments with heavy ions near the coulomb barrier within the super-heavy element (SHE) research project a multi-stage R&D program of GSI, HIM and IAP is currently in progress. It aims at developing a superconducting (sc) continuous wave (cw) LINAC with multiple CH cavities as key components downstream the upgraded High Charge Injector (HLI) at GSI. The LINAC design is challenging, due to the requirement of intense beams in cw-mode up to a mass-to-charge-ratio of 6 while covering a broad output energy range from 3.5 to 7.3 MeV/u with minimum energy spread. The next milestone will be a full performance beam test of the first expansion stage at GSI, the Demonstrator, comprising two solenoids and a 15-gap CH cavity inside a cryostat. |
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| DOI • | reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOY023 | |
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| MOPOY024 | Development of a 325 MHz Ladder-RFQ of the 4-Rod-Type | 899 |
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| In order to have an inexpensive alternative to 4-Vane RFQs above 200 MHz, we study the possibilities of a Ladder-RFQ. The 325 MHz RFQ is designed to accelerate protons from 95 keV to 3.0 MeV according to the design parameters of the research program with cooled antiprotons at FAIR. This particular high frequency for an RFQ creates difficulties, which are challenging in developing a cavity. In order to define a satisfactory geometrical configuration for this resonator, both from the RF and the mechanical point of view, different designs have been examined and compared. Very promising results have been reached with a ladder type RFQ, which has been investigated since 2013. Due to its geometric size the manufacturing as well as maintenance is not that complex compared with welded accelerators. The manufacturing, coppering and assembling of a 0.8 m prototype RFQ is finished. We present recent measurements of the rf-field, frequency-tuning, field flatness and the mode spectrum. | ||
| DOI • | reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOY024 | |
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| WEPOY009 | Simulation Study of Emittance Growth from Coulomb Explosion in a Charge Separator System After Stripping | 3005 |
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Funding: BMBF-05P15RFRBA A computer 3D particle-in-cell (PIC) simulation is used to examine the emittance growth of an intense heavy ion beam after a charge stripper. Multi-species dynamics of the bunched uranium beam with various charge states and including compensation electrons will be presented. The rms-emittance growth shows different behaviour in the horizontal, vertical and longitudinal planes, dependent on initial conditions, like a bunch size, beam current and phase space ellipse orientation. An optimization of initial parameters is therefore crucial for a successful and efficient post-acceleration. The role of the separation system and of co-moving electrons will be discussed for the example of the GSI-Unilac. |
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| DOI • | reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPOY009 | |
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