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| MOMPMP01 |
Computational Beam Dynamics for SNS Commissioning and Operation
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simulation, space-charge, electron, linac |
1 |
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- J. A. Holmes, S. M. Cousineau, V. V. Danilov, S. Henderson, D.-O. Jeon, M. A. Plum, A. P. Shishlo, Y. Zhang
ORNL, Oak Ridge, Tennessee
- D. A. Bartkoski
UTK, Knoxville, Tennessee
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Funding: SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U. S. Department of Energy.
The computational approach is providing essential guidance and analysis for the commissioning and operation of SNS. Computational models are becoming sufficiently realistic that it is now possible to study detailed beam dynamics issues quantitatively. Increasingly, we are seeing that the biggest challenge in performing successful analyses is that of knowing and describing the machine and beam state accurately. Even so, successful benchmarks with both theoretical predictions and experimental results are leading to increased confidence in the capability of these models. With this confidence, computer codes are being employed in a predictive manner to guide the machine operations. We will illustrate these points with various examples taken from the SNS linac and ring.
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| MOA2IS01 |
The ORBIT Simulation Code: Benchmarking and Applications
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electron, simulation, space-charge, impedance |
53 |
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- A. P. Shishlo, S. M. Cousineau, V. V. Danilov, J. Galambos, S. Henderson, J. A. Holmes, M. A. Plum
ORNL, Oak Ridge, Tennessee
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Funding: SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U. S. Department of Energy.
The contents, structure, implementation, benchmarking, and applications of ORBIT as an accelerator simulation code are described. Physics approaches, algorithms, and limitations for space charge, impedances, and electron cloud effects are discussed. The ORBIT code is a parallel computer code, and the scalabilities of the implementations of parallel algorithms for different physics modules are shown. ORBIT has a long history of benchmarking with analytical exactly solvable problems and experimental data. The results of this benchmarking and the current usage of ORBIT are presented.
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| TUMPMP01 |
Simple Maps in Accelerator Simulations
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electron, ion, simulation, vacuum |
81 |
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- S. Peggs, U. Iriso
BNL, Upton, Long Island, New York
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Difference systems (described by maps) exhibit much richer dynamical behavior than differential systems, because of the emphasis they place on occasional "high-frequency" transient kicks. Thus, the standard map (with pulsed gravity) displays chaos, while the gravity pendulum does not. Maps also speed up simulations enormously, by summarizing complex dynamics in short form. A new example of richer bahavior, and of dramatic speed up, comes from the representation of interacting electron clouds and ion clouds. Coupled maps are capable of demonstrating the first order phase transitions (from cloud "off" to "on") that are sometimes observed in practice, and enable the extension of electron cloud simulation to include much slower evolving ion clouds.
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| TUPPP01 |
DEE Voltage Calibration for the ACCEL Proton Therapy Cyclotron
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cyclotron, electron, vacuum, extraction |
102 |
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- J. H. Timmer, P. A. Komorowski, H. Röcken
ACCEL, Bergisch Gladbach
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ACCEL Instruments GmbH has developed a superconducting cyclotron for the use in proton therapy systems. An essential step during the commissioning of the medical cyclotron is the calibration and balancing of the DEE voltages. Using a very compact and low cost X-ray detector the bremsstrahlung spectrum of stray electrons accelerated by the four RF cavities has been measured. To determine the peak voltage a regression analysis of the measured spectrum has been carried out using a non-linear multiple convolution model taking into account the energy gain of the stray electrons between the liner and the DEE, the bremsstrahlung spectrum integrated over angle as well as the attenuation effects caused by the liner and the limited detector resolution. The correlation between the model and the measurement was very good. A software tool enabling automatic spectrum acquisition and analysis capable of online determination of the DEE voltages has been developed in LabVIEW graphical programming environment. Careful balancing of the DEE voltages resulted in better beam focusing and a cyclotron extraction efficiency larger than 80%. The absolute acceleration voltage has been confirmed by turn-separation measurements.
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| WEPPP11 |
Comparison of the Beam Dynamics Designs for the FAIR High Current Proton LINAC-RFQ
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rfq, emittance, linac, simulation |
205 |
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- S. Yaramyshev, W. Barth, L. A. Dahl, L. Groening
GSI, Darmstadt
- A. P. Durkin
MRTI RAS, Moscow
- S. Minaev
ITEP, Moscow
- A. Schempp
IAP, Frankfurt-am-Main
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The antiproton physics program for future Facility for Antiproton and Ion Research (FAIR) at Darmstadt is based on a rate of 7·1010 cooled antiprotons per hour. To provide sufficient primary proton intensities a new proton linac is planned. The proposed linac comprises an Electron Cyclotron Resonance (ECR) proton source, a Radio Frequency Quadrupole (RFQ), and Crossed-bar H-cavities (CH). Its operation frequency of 352 MHz allows for an efficient acceleration to up to 70 MeV using normal conducting CH-DTLs. The beam pulses with a length of 32 mks, a current of 70 mA, and total transverse emittances of 7 mkm will allow to fill the existing GSI synchrotron SIS 18 within one multi-turn-injection up to its space charge limit of 7·1012 protons. Conceptual RFQ designs for two different RFQ types are proposed simultaneously: an RFQ of 4-rod type from the University Frankfurt and a 4 windows type RFQ from Institute for Theoretical and Experimental Physics (ITEP) and Moscow Radio-Technical Institute (MRTI). Studies of the beam dynamics in both RFQs has been done with the versatile multi-particle code DYNAMION. The topology of the RFQ tanks and electrodes is used "as to be fabricated" to provide for the realistic calculations of the external electrical field. The simulations are done under space charge conditions and including influence of the possible misalignments and errors of the fabrication. Simulated results for both designs will be discussed, as well as pros and cons. A comparison of the DYNAMION results with the simulations done by means of the PARMTEQM and LIDOS (dedicated codes for an RFQ design) is presented.
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| WEA1MP03 |
Computing Methods in FFAG Accelerators Design
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factory, emittance, magnet-design, optics |
238 |
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- F. Meot
CEA, Gif-sur-Yvette
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There has recently been a regain of interest of Fixed Field Alternating Gradient (FFAG) accelerators, the use of which use is now envisaged in various domains, from the fast acceleration of muon beams in the Neutrino Factory, to high average intensity medical beams, via proton and other electron driver applications. The capability of computer codes to model the FFAG type of accelerator and to perform precision tracking is a concern, in design stages, from both point of views of optics and of magnet design. The difficulties come mainly from, (i) the reference orbit moving with energy, in relation with the large momentum bite in these machines, (ii) the presence of possibly very strong sources of non-linearities, as fields and kinematical effects, (iii) the necessity of exploring large amplitude motion inherent to the capacity of FFAGs to accelerate very large emittances. These questions, the way they are addressed, and the methods/codes in use nowadays to perform FFAG studies will be reviewed. This will be illustrated with contemporary problems, drawn from the Neutrino Factory, medical application of FFAGs, etc.
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