| Paper | Title | Page |
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| TPPE029 | Measurements of Ion Selective Containment on the RF Charge Breeder Device BRIC | 2065 |
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Funding: Istituto Nazionale Fisica Nucleare. The "charge state breeder" BRIC (BReeding Ion Charge) is based on an EBIS source and it is designed to accept Radioactive Ion Beam (RIB) with charge +1, in a slow injection mode, to increase their charge state up to +n. BRIC has been developed at the INFN section of Bari (Italy) during these last 3 years with very limited funds. Now, it has been assembled at the LNL (Italy) where are in progress the first tests as stand alone source. The new feature of BRIC, with respect to the classical EBIS, is given by the insertion, in the ion drift chamber, of a Radio Frequency (RF) Quadrupole aiming to filtering the unwanted elements and then making a more efficient containment of the wanted ions. In this contribution, the measurements of the selective effect on the ion charge state containement of the RF quadrupole field, applied on the ion chamber, will be reported and discussed. The ion charge state analisys of the ions trapped in BRIC seem confirm, as foreseen by simulation results carried out previously, that the selective containment can be obtained. A modification of the collector part to improve the ion extraction of BRIC will be also presented and shortly discussed. |
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| TPPE030 | A Method to Polarize Stored Antiprotons to a High Degree | 2158 |
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The PAX collaboration proposes a method to produce intense beams of polarized antiprotons. Polarized antiprotons can be produced in a storage ring by spin-dependent interaction in a purely hydrogen gas target. The polarizing process is based on spin transfer from the polarized electrons of the target atoms to the orbiting antiprotons. After spin filtering for about two beam lifetimes at energies of about 50-100 MeV using a dedicated large acceptance ring, the antiproton polarization would reach P=0.2-0.4. In the presentation, beside a description of the polarization technique and its potentiality, a description of the ideal characterstics of the antiproton polarizer will be given.
hep-ph/0411046 |
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| TPPE031 | 60 mA Carbon Beam Acceleration with DPIS | 2206 |
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| We have studied "direct plasma injection scheme (DPIS)" since 2000. This new scheme is for producing very intense heavy ions using a combination of an RFQ and a laser ion source. An induced laser plasma goes directly into the RFQ without an extraction electrode nor any focusing devices. Obtained maximum peak current of Carbon 4+ beam reached 60 mA with this extremely simple configuration. The details of the experimental result will be presented. | ||
| TPPE032 | Particle-in-Cell Simulations of the VENUS Ion Beam Transport System | 2236 |
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Funding: This work was supported by the Director, Office of Energy Research, Office of High Energy and Nuclear Physics, Nuclear Physics Division of the U.S. DOE under Contract DE AC03-76SF00098 The next-generation superconducting ECR ion source VENUS serves as the prototype injector ion source for the linac driver of the proposed Rare Isotope Accelerator (RIA). The high-intensity heavy ion beams required by the RIA driver linac present significant challenges for the design and simulation of an ECR extraction and low energy ion beam transport system. Extraction and beam formation take place in a strong (up to 3T) axial magnetic field, which leads to significantly different focusing properties for the different ion masses and charge states of the extracted beam. Typically, beam simulations must take into account the contributions of up to 30 different charge states and ion masses. Two three-dimensional, particle-in-cell codes developed for other purposes, IMPACT and WARP, have been adapted in order to model intense, multi-species DC beams. A discussion of the differences of these codes and the advantages of each in the simulation of the low energy beam transport system of an ECR ion source is given. Direct comparisons of results from these two codes as well as with experimental results from VENUS are presented. |
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| TPPE033 | A Comparison of Electrostatic and Magnetic Focusing of Mixed Species Heavy Ion Beams at NSCL/MSU | 2281 |
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Funding: This work has been supported by National Science Foundation under grant PHY-0110253. Experience at the National Superconducting Cyclotron Laboratory has shown the first focusing element after the electron cyclotron resonance ion source (ECRIS), before the beam is analyzed by a magnetic dipole, to be critical to subsequent beam transport and matching. Until 2004, both ion sources at the NSCL used a solenoid as this first focusing element. Observation of hollow beam formation led to further analysis and the decision to replace the solenoid with an electrostatic quadrupole triplet on a test basis [1]. Substantial increases in net cyclotron output were achieved, leading us to adopt electrostatic quadrupole focusing as the permanent configuration. In addition, a sextupole magnet was installed in this beam line. Motivations for these changes and results of operating experience are discussed. |
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| TPPE034 | Possible Scheme of the Analyzing Part of a Cyclotron Injection Beamline with Higher Energy | 2345 |
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Funding: This work was supported in part by the National Science Foundation under grant PHY-0110253. The ion beam produced with an ECR ion source (ECRIS) with an extraction voltage of 30 kV may be additionally accelerated using a negative voltage of -30 kV applied to the last electrode of the extraction system, connected to the beamline biased to the same -30 kV potential. In this way the kinetic energy of the beam is increased to 60 keV/q, decreasing to half the space charge effect on the beam emittance. Using a large gap analyzing magnet placed right after the ECRIS and no focusing element, the transmission is still close to 100%. The voltage on the beamline must be kept constant from the ECRIS till the image focal plane of the analyzing magnet where the full separation of the beam charge states is achieved. An insulator break separates the biased beamline from the downstream section, which is at zero potential. Passing through this section of the beamline, the ion beam is decelerated to 30 keV/q, the energy necessary for the injection in the cyclotron. In order to prevent the increase of the beam divergence, a focusing solenoid is installed behind the break point. This work will present the results of a simulation of the transport of an argon beam in the proposed beamline. |
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| TPPE035 | Efficiency of the Fermilab Electron Cooler’s Collector | 2387 |
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Funding: Operated by Universities Research Association Inc. under Contract No. DE-AC02-76CH03000 with the United States Department of Energy. The newly installed high-energy Recycler Electron Cooling system (REC) at Fermilab will work at an electron energy of 4.34 MeV and a DC beam current of 0.5 A in an energy recovery scheme. For reliable operation of the system, the relative beam current loss must be maintained to levels < 3.e-5. Experiments have shown that the loss is determined by the performance of the electron beam collector, which must retain secondary electrons generated by the primary beam hitting its walls. As a part of the Electron cooling project, the efficiency of the collector for the REC was optimized, both with dedicated test bench experiments and on two versions of the cooler prototype. We find that to achieve the required relative current loss, an axially-symmetric collector must be immersed in a transverse magnetic field with certain strength and gradient prescriptions. Collector efficiencies in various magnetic field configurations, including without a transverse field on the collector, are presented and discussed |
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| TPPE036 | Progress of the BEPCII Linac Upgrade | 2416 |
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| BEPCII-an upgrade project of the BEPC is a factory type of e+e- collider. It requires its injector linac to have a higher beam energy (1.89 GeV) for on-energy injection and a higher beam current (40 mA e+ beam) for a higher injection rate (=50 mA/min.). The low beam emittance (1.6pmm-mrad for e+ beam, and 0.2pmm-mrad for 300 mA e- beam) and low beam energy spread (±0.5%) are also required to meet the storage ring acceptance. Hence we need a new electron gun system, a new positron source, a much higher power and more stable RF system with its phasing loops, and a new beam tuning system with orbit correction. Up to date, all system design and fabrication work have been completed. And in five months from May 1st of 2004, the positron production system–from the electron gun to the positron source, has been installed into the tunnel. In this paper, we will introduce major upgrades of each system, and present the recent beam commissioning. | ||
| TPPE037 | Relative Contribution of Volume and Surface-Plasma Generation of Negative Ions in Gas Discharges | 2482 |
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| The relative contribution of volume and surface-plasma generation of extracted ?- ions in gas discharge sources will be analyzed. At the present time, it is well known that surface-plasma generation of extracted ?- ion is dominate above volume processes in discharges with admixture of cesium or other catalysts with low ionization potential. We will attract attention to evidences, that surface-plasma generation can be enhanced in high density discharges without cesium after electrode activation by high temperature conditioning in discharge. A diffusion of impurity with a low ionization potential can be a reason of observed enhancement of H- emission. For the effective generation of ?- ion beams in discharge without cesium, it is necessary to optimize surface-plasma generation of extracted ?- ion. Such optimization allows considerable improvement of ?-/D- sources characteristics. | ||
| TPPE038 | Thermal Hydraulic Design of PWT Accelerating Structures | 2524 |
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Funding: Work supported by DOE SBIR Grant No. DE-FG02-03ER83846. Microwave power losses on the surfaces of accelerating structures will transform to heat which will deform the structures if it is not removed in time. Thermal hydraulic design of the disk and cooling rods of a Plane Wave Transformer (PWT) structure is presented. Experiments to measure the hydraulic (pressure vs flow rate) and cooling (heat removed vs flow rate) properties of the PWT disk are performed, and results compared with simulations using Mathcad models and the COSMOSM code. Both experimental and simulation results showed that the heat deposited on the structure could be removed effectively using specially designed water-cooling circuits and the temperature of the structure could be controlled within the range required. |