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Wider availability of PARMILA and recent improvements to PARMILA
Get PDFPARMILA (Phase And Radial Motion in Ion Linear Accelerators) is a drift-tube linac (DTL) ion-beam dynamics code. Over its long life, many versions have developed. The Los Alamos Accelerator Code Group distributes a version, for which a manual is available. Unless otherwise specified, all mentions of PARMILA in this document refer to that LAACG-distributed version. Until recently, this documented and distributed version functioned only under CTSS. Users who wished to run on a different operating system needed to convert the code themselves. PARMILA now operates under UNICOS, a much more widely available CRAY operating system, and under VAX/VMS. This paper describes some new features of the code, and gives directions for obtaining the manual and the UNICOS and VMS versions of the code
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Wider availability of PARMILA and recent improvements to PARMILA
Get PDFPARMILA (Phase And Radial Motion in Ion Linear Accelerators) is a drift-tube linac (DTL) ion-beam dynamics code. Over its long life, many versions have developed. The Los Alamos Accelerator Code Group distributes a version, for which a manual is available. Unless otherwise specified, all mentions of PARMILA in this document refer to that LAACG-distributed version. Until recently, this documented and distributed version functioned only under CTSS. Users who wished to run on a different operating system needed to convert the code themselves. PARMILA now operates under UNICOS, a much more widely available CRAY operating system, and under VAX/VMS. This paper describes some new features of the code, and gives directions for obtaining the manual and the UNICOS and VMS versions of the code
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PARMILA (Phase And Radial Motion In Linear Accelerators): An introduction
No full textThis is a tutorial overview of the PARMILA drift-tube linac beam-dynamics code. First discussed are what PARMILA is and what it is used for. Its origins are discussed. What PARMILA does and how it does its tasks are described. One of the major uses of PARMILA is for the evaluation of effects produced by errors in construction and deviations from design operating conditions. In this connection, a few words are said about what errors PARMILA is able to handle. A section on user friendliness is followed by a few words on the code's accuracy. Finally, some options and improvements are proposed
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Modified PARMILA code for new accelerating structures
Get PDFThe PARMILA code was originally developed as a numerical tool to design and simulate the beam performance of the drift-tube linac (DTL). The authors have extended PARMILA to the design of both the coupled-cavity linac (CCL) and the coupled-cavity drift-tube linac (CCDTL). They describe the new design and simulation features associated with these linac structures and improvements to the code that facilitate a seamless linac design process
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Radial particle distributions in PARMILA simulation beams
No full textThe estimation of beam spill in particle accelerators is becoming of greater importance as higher current designs are being funded. To the present, no numerical method for predicting beam-spill has been available. In this paper, we present an approach to the loss-estimation problem that uses probability distributions fitted to particle-simulation beams. The properties of the PARMILA code's radial particle distribution are discussed, and a broad class of probability distributions are examined to check their ability to fit it. The possibility that the PARMILA distribution is a mixture is discussed, and a fitting distribution consisting of a mixture of two generalized gamma distributions is found. An efficient algorithm to accomplish the fit is presented. Examples of the relative prediction of beam spill are given. 26 references, 18 figures, 1 table
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Recent developments in the accelerator design code PARMILA
No full textThe PARMILA code, which originated in the 1960s for designing drift-tube linacs (DTLs), now designs and simulates the performance of many types of rf linear accelerator. The structure types include the DTL, coupled-cavity drift-tube linac (CCDTL), conventional coupled-cavity linac (CCL), and several types of superconducting linac. This new code can handle multiple types of linac structures in a single run. This code features a more logically organized input sequence for the different linac structures and their properties. A PARMILA run can include sequences of beam-transport elements. In this paper, the authors describe the new user interface, highlighting the implementation of multiple rf structures. Also, they discuss the algorithm used for designing superconducting linac structures
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Beam Dynamics Simulations using a Parallel Version of PARMILA
Get PDFThe computer code PARMILA has been the primary tool for the design of proton and ion linacs in the United States for nearly three decades. Previously it was sufficient to perform simulations with of order 10000 particles, but recently the need to perform high resolution halo studies for next-generation, high intensity linacs has made it necessary to perform simulations with of order 100 million particles. With the advent of massively parallel computers such simulations are now within reach. Parallel computers already make it possible, for example, to perform beam dynamics calculations with tens of millions of particles, requiring over 10 GByte of core memory, in just a few hours. Also, parallel computers are becoming easier to use thanks to the availability of mature, Fortran-like languages such as Connection Machine Fortran and High Performance Fortran. We will describe our experience developing a parallel version of PARMILA and the performance of the new code
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Transverse Match of High Peak-Current Beam into the LANSCE DTL Using PARMILA
Get PDFA new algorithm that uses a multiparticle PARMILA-based code to match high peak current H{sup +} beam ({approx}21 mA) into the Los Alamos Neutron Science Center (LANSCE) drift tube linac (DTL) has been developed. Two single cell rf bunchers in the low energy beam transport (LEBT) prepare the initially unbunched beam for DTL capture. The transverse distribution at the entrance to the DTL is set with four quadrupoles in the 1.26 m between the last transverse emittance measuring station and the DTL entrance. Previous matching algorithms used TRACE and TRACE 3-D to determine these quadrupole strengths. PARMILA simulation show this procedure produces non-zero mismatch and additional emittance growth through the DTL for high current beams. Because of strong space-charge forces and a rapidly forming longitudinal bunch, simple envelope calculations do not model the beam evolution in the LEBT well. A PARMILA model of this region was combined with ant iterative search routine to set the LEBT quadrupole strengths to achieve a better transverse match into the DTL. Simulations predict a significant reduction in transverse emittance at the exit of the DTL over the typical TRACE 3-D result
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Improvements to PARMILA
Get PDFPARMILA is an internationally accepted standard for Monte Carlo simulation of linac and transport line performance. We discuss several modifications and improvements to this code. A generalized magnet routine allows the simulation of electrostatic and magnetic quadrupoles, solenoids, sextupoles, and octupoles. Optional inclusion of linear fringe fields and/or geometric aberrations is provided for in the quadrupole transformation. The dipole routine has been replaced with a more accurate algorithm. The accelerating gap transformation has been replaced by a set of implicit equations which accurately describe the relativistic particle behavior in the presence of longitudinal and transverse electric fields described by a set of 6 weighted Fourier moments (transit time factors). A simple model allows these moments, in turn, to be approximated from the cell geometry and the usual T and S functions. A number of added convenience features - interactive disk storage and retrieval of particle coordinates, individual particle input and observations, an interactively callable test for particle longitudinal stability, and an automated quadrupole tuning procedure - all add to the code's versatility, convenience, and strength as a design tool
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Linear accelerator modeling: development and application. [PARMILA]
No full textMost of the parameters of a modern linear accelerator can be selected by simulating the desired machine characteristics in a computer code and observing how the parameters affect the beam dynamics. The code PARMILA is used at LAMPF for the low-energy portion of linacs. Collections of particles can be traced with a free choice of input distributions in six-dimensional phase space. Random errors are often included in order to study the tolerances which should be imposed during manufacture or in operation. An outline is given of the modifications made to the model, the results of experiments which indicate the validity of the model, and the use of the model to optimize the longitudinal tuning of the Alvarez linac
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