Virtual Accelerator at J-PARC 3 GeV Rapid Cycling Synchrotron

1. ▲ SNS Operation Interface (OPI) Control server with runtime database (EPICS IOCs) Real Accelerator Magnets RF Monitors Errors Virtual Accelerator Magnets RF Monitors Errors Virtual Accelerator at J-PARC 3 GeV Rapid Cycling Synchrotron H. Harada*, K. Shigaki (Hiroshima University in Japan), H. Hotchi, F. Noda, H. Sako, H. Suzuki, Y. Irie (JAEA in Japan), K. Furukawa (KEK in Japan), S. Machida (CCLRC RAL in UK) * 1st Author : Hiroyuki Harada, Email : harada@hepl.hiroshima-u.ac.jp J-PARC Abstract : We have developed a Virtual Accelerator at 3 GeV Rapid Cycling Synchrotron (RCS) in J-PARC. It has a simulator of beam in the complicated accelerator and is put out under the control server as well as a real machine. It is possible to do a dry run without beam, and consequently gives a strong feedback for the RCS operation as a commissioning tool. Therefore, we can examine the control system for the real machine and practice the commissioning of the real machine by using the Virtual Accelerator. It is important to have the tool based on beam dynamics for the performance gain of an accelerator. Consequently, it will lead a physics run for experiments of the science at the J-PARC to success or a better run. We present the concept of the control system including the Virtual Accelerator and construction of itself. J-PARC Facility Frontier of High Intensity ●：Existing ▲：Under commissioning or construction ☆ Accelerators at J-PARC ▼ 400 MeV (181 MeV at phase-1) LINAC ▼ 3 GeV 25 Hz Rapid Cycling Synchrotron (RCS) ▼ 50 GeV Main Ring Synchrotron (MR) ☆ Facility at J-PARC ▼ Materials and Life Science Facility (from 3 GeV RCS) ▼ Nuclear and Particle Physics Experimental Hall (from 50 GeV MR) ▼ Neutrino Facility (from 50 GeV MR) ☆1MW@3 GeV RCS 6 times at ISIS as Neutron Source ☆0.75 MW@50 GeV MR 5 times at AGS as Proton/Second Particle Source Increasing attention to MR from region of Nuclear-Particle Physics Materials-Life Sciences This Project 3GeV Power ▲ Nuclear-Particle Physics This Project 50GeV ▲ 1 MW 0.1 MW Presented by Nagamiya Director at ATAC’06 3 GeV RCS The total acceptable beam loss rate < 10-3 (1kW) → extremely lower than that of usual accelerators • Major Sources of beam loss • Betatron tune shift from space charge effect • Increasing nonlinear field components from large aperture magnets • Interference of fringe fields between magnets Table. Parameters of J-PARC Rings and BNL AGS The total acceptable beam loss rate at RCS is less than 10-3 (1kW) and RCS has many sources of beam loss caused by high intensity. If total beam loss exceeds 1W/m except for the collimator region, it is impossible to do maintenance of activated elements in the ring. Therefore, we need to avoid excess beam loss with 1MW high intensity beam. However, we cannot justify a suitable parameter set of all elements with only experience because we must consider the sources of beam loss with nonlinear components. So, it is very important to have a tool with a complex calculation. The tool based on beam dynamics and simulation should be used to find inputting error of the setting value and to judge whether the setting value of magnets is justified or not. Modeling of Virtual Accelerator Concept of Virtual Accelerator We develop the control system for an accelerator added Virtual Accelerator (VA) at 3 GeV RCS in J-PARC. The VA is a simulator of beam in the complicated accelerator based on beam dynamics, for simulation of the beam behavior in the ring. The targeted control system is shown in the flow chart. We have implemented the elements into VA, for modeling of a real machine. * Magnets This is the element for deflecting, focusing, defocusing and correction etc. Beam is given a kick by main component field, higher order nonlinear fields and fringe field. * RF Cavity This is the element for increasing and decreasing energy. Beam is given an energy by gap voltage. * Exciter This is the element for excitation of the beam transverse oscillation. * Beam Position Monitor (BPM) This is the monitor for getting the transverse beam position and have a finite resolution σ. • OPI (Operation Interface) : • The control terminal to control the elements, such as Magnets, RF cavity and Monitors • EPICS (Experimental Physics and Industrial Control System) : • A set of Open Source software tools, libraries and applications • Creation of distributed soft real-time control systems for scientific instruments such as a particle accelerators etc • Use of Client/Server and Publish/Subscribe techniques to communicate between various computers • The control server called IOCs including runtime database • Input and Output to IOCs using the Cannel Access (CA) network protocol. A dry run on Virtual Accelerator Flow chart of the control system for an accelerator based on Virtual Accelerator We have created the preliminary OPI to measure the basic parameters and have virtually measured the parameters on VA for the storage mode in the commissioning phase at 3 GeV RCS. We introduce the OPI and the result of measurement of betatron tune by a dry run, for example. We put VA modeled a real machine out under the IOCs based on EPICS and operate VA like a real machine. This is a originality control model. It is shown advantage of this model in the following below. Advantage of the control model with VA : ＊ Give a strong online feedback based on beam dynamics ＊ Judge whether setting parameters are justified or not ＊ Examine the control system of the machine ＊ Practice commissioning of the machine To log the Tune X & Y • A common method to measure betatron tune • Excite transverse beam motion by exciter • Detect the transverse beam position • Do frequency analysis by FFT plot the result FFT and search the tune peak Construction of Control System including Virtual Accelerator operate the Exciter OPI We have constructed the control system of VA through control server. It is possible to operate VA like a real machine from OPI through IOCs. OPI→ SAD TkInter developed by KEK IOCs → EPICS toolkit developed by collaboration VA→ Virtual Accelerator OPI for measurement of betatron tune Get beam position from monitors Input setting value to magnets etc Summary : We have developed a Virtual Accelerator based on EPICS at 3 GeV Rapid Cycling Synchrotron (RCS) in J-PARC. This is expected as a tool to give a strong feedback to a real machine and avoid beam loss over the acceptable one. It is important to have the tool in high intensity proton machine such as RCS. The Virtual Accelerator built into the same control system with a real machine is possible to do a dry run without a beam and examine the operation or commissioning algorithm before it is actually executed in a real machine. We have implemented some elements into Virtual Accelerator, for modeling of a real machine. Additionally, we have been successful to build it into control system. We have had a virtually operation and measure basic parameters on Virtual Accelerator for the storage mode in the commissioning stage at the 3 GeV RCS. In the future, we have tasks to be improved in order to conform to a real machine and operate it in a real time. It is to add an space charge effect and acceleration process to Virtual Accelerator, and to speed up the calculation. IOCs Get beam position from monitors Input setting value to magnets etc VA A basic control system for Virtual Accelerator The VA is input setting value of elements through IOCs and run a simulation with particles tracking calculation. As the result, OPI gets beam position on monitors through IOCs.