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The virtual accelerator concept

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www.cea.fr
www.cea.fr EUCARD2/MAX ACCELERATORS FOR ACCELERATOR DRIVEN SYSTEMS WORKSHOP
20-21 MARCH 2014.
URIOT Didier
| PAGE 1
The virtual
accelerator concept
23 SEPTEMBRE 2014
| PAGE 2
CEA | 10 AVRIL 2012
Generalities
Operating modes
Limitations
Implementation
Experimentations
Perspectives
SOME GENERALITIES
23 SEPTEMBRE 2014 | PAGE 3
EuCARD2/MAX
A virtual Accelerator a simulation code connected with the control system of a real
machine.
Virtual: because from the viewpoint of the control system command, the simulation code
is seen as a real machine.
Two different approaches to implement it:
Integrate the simulation model into the control system (XAL @SNS, J-PARC…)
Integrate a part of the control system into the simulation code (Traxce3D)
Two different groups involved:
Beam dynamics group
Control command group
In the second approach Virtual Accelerator is proposed and developed as an independent high level
application of the control system.
« A Virtual Accelerator is a computer process which simulates the behavior of a beam in an
accelerator and responds to the accelerator control program under development in a same
way as an actual accelerator do
OPERATING MODES
23 SEPTEMBRE 2014 | PAGE 4
EuCARD2/MAX
Different operating modes have been identified
Control tower
Flight simulator
Autopilot
For each of them what are?
oImprovements expected for the accelerator physicist or operator
oDifficulties to implement
oWorkload
Global control system IHM
Low level
Set a power supply
Read a beam current
Intermediate level
Insert a profiler to calculate
beam rms values
High level applications
Tune a beam size
Align the beam
Virtual
accelerator
CONTROL TOWER” MODE
23 SEPTEMBRE 2014 | PAGE 5
EuCARD2/MAX
Control system interface
Diagnostics
Equipment
Real machine
equipment database
Tuning
Algorithms
Visualisations
Action on the control system of the machine
acts at the same time on the real accelerator
and on the virtual one.
Automatic or periodic synchronization
The machine is under the constant supervision
of the virtual machine. Its monitored by the
simulation code
Virtual accelerator only code needs read-only
access to the accelerator database.
Interest for beam physicists: Direct comparison between the real diagnostics and simulated accelerator.
Improvement of simulation codes, better understanding of the accelerator is also expected.
Interests for machine operation: direct and comprehensive visualization (envelopes, space phases, all
beam parameters, diagnostics, etc.) at all accelerator locations.
FLIGTH SIMULATOR” MODE
23 SEPTEMBRE 2014 | PAGE 6
EuCARD2/MAX
Control system interface
Diagnostics
Equipment
Virtual accelerator
database
Real accelerator
database
Tuning
Algorithms
Visualizations
Action on the control system is applied either to
virtual or on the real accelerator.
There are actually two separate machines; the real
accelerator and its simulator or VA.
That implies 2 independent data bases or a single
data base containing separate fields representing the
states and values of real and virtual machine devices.
HIM control system must allow to switch easily and
securely from a data base to the other.
Possibly to copy a database to the other
Simulation code only needs read-only access to the
virtual database
Very complex in term of architecture and no
development is planned today
Interest for machine physicists: Users of the virtual accelerator can evaluate settings or tuning procedures or
new algorithms before testing on the real machine without disturbing operation of the accelerator.
Interests for machine operation: Preview what we are preparing to order on the machine allows to avoid
serious errors and save time in case of complicated adjustments. This mode also has an obvious advantage in training,
even during the machine operation.
AUTOPILOT” MODE
23 SEPTEMBRE 2014 | PAGE 7
EuCARD2/MAX
Control system
interface
Diagnostics
Equipment
Real accelerator
database
Tuning
Algorithms
Visualizations
Modern codes get abilities to tune simulated
machine only taking account diagnostics information.
Use the automatic features of the code to also
directly tune the real machine.
In this mode HIM control system of the machine is
replaced by the GUI simulation code.
The code uses diagnostics measurements from the
real machine as input of its algorithm to control real
machine equipment.
The code have to get read and write access to
machine database
Modeling program is not used here.
Interest for machine physicists: development and checking, the procedures and algorithms
of automatic tuning of parts or the whole machine. The simulator code often propose much more
flexibility.
Interests for machine operation: complex, delicate, or tedious adjustments can be made
automatically and much faster. Very useful, when high level applications of the control system are
missing One of the main motivation at Saclay.
GENERAL SYNOPTIC
23 SEPTEMBRE 2014 | PAGE 8
EuCARD2/MAX
Control system interface
Diagnostics
Equipment
Virtual accelerator
database
Real accelerator
database
Tuning Algorithms
Visualizations
Our objectives:
A ‘light’ solution requiring a small
development group.
Compensating high level tuning applications
missing for IPHI and Spiral2 commissioning
Autopilotmode was the priority.
Code (from CEA) :TraceWin
Control system :EPICS
Development started in 2006 and focused
in “Autopilot” mode.
LIMITATIONS
23 SEPTEMBRE 2014 | PAGE 9
EuCARD2/MAX
Simulation duration:
According to the model used, accelerator simulation is often not as fast as the
real machine.
In envelop mode : a few seconds
Tracking mode : depend of the number of particles and model used to describe
elements.
Today, it’s seem complicated to expect RFQ integration into a virtual machine.
Predictability:
Higher is energy, higher is the quality of the predictability of the codes.
Safety:
Autopilot” mode for replacing high level applications by simulation code, seem
ambitious for high power beam. Clearly, plug it into a MW machine is not for
tomorrow. Its a huge challenge.
TRACEWIN CODE
23 SEPTEMBRE 2014 | PAGE 10
EuCARD2/MAX
Everything about beam is knew, everywhere
TRACEWIN CODE
23 SEPTEMBRE 2014 | PAGE 11
EuCARD2/MAX
A very easy way to defined tuning procedure
scripts
Why don’t use these capabilities directly on the
real machine ?
TRACEWIN CODE + VA
(*) PROCESS VARIABLE | PAGE 12
EuCARD2/MAX
SIMULATIONS
Tracking
GUI : (C++) + lib Qt4
Real accelerator Virtual accelerator
TraceWin EPIC PVs
- Elements
- Diagnostics
- Command PVs (*)
- Acquisition PVs
- Monitoring PVs
(C++) + Lib EPICS Accelerator description :
- Structure, elements list
- Diagnostics
- Errors
Tuning scripts
Association : Elements Diagnostics
Tuning processes
Optimization algorithms
Envelop
TraceWin core : (C++ & Fortran)
Graphic interface
Exploitation of results :
Plots
Distributions
Beam parameters
• …
Archi. Client Server
Statistical study
Input beams
Channel Access
FIRST STEP OF “AUTOPILOT” MODE
23 SEPTEMBRE 2014 | PAGE 13
EuCARD2/MAX
Tracking
GUI : (C++) + lib Qt4
Real accelerator Virtual accelerator
TraceWin EPIC PVs
- Elements
- Diagnostics
- Command PVs
- Acquisition PVs
- Monitoring PVs
(C++) + Lib EPICS Accelerator description :
- Structure, elements list
- Diagnostics
- Errors
Tuning scripts
Association : Elements Diagnostics
Tuning processes
Optimization algorithms
Envelop
TraceWin core : (C++ & Fortran)
Graphic interface
Exploitation of results :
Plots
Distributions
Beam parameters
• …
Archi. Client Server
Statistical study
Input beams
Channel Access
SIMULATIONS
AUTOPILOT” TOOL
23 SEPTEMBRE 2014 | PAGE 14
EuCARD2/MAX
Based on TraceWin technologies (class)
- Elements & diagnostics
- Tuning scripts
- Algorithms
- GUI
Objectives:
Check the Epics Chanel Access Client
Injectors commissioning
FIRST TEST, SILHI
23 SEPTEMBRE 2014 | PAGE 15
EuCARD2/MAX
Beam injection through the
cone have been optimized.
Beam parameters of RFQ
injection have been validated
It’s planned to use VA to tune
LEBT+RFQ+HEBT.
Manually, 1 day, 80%
VA, 10 minutes, 90%
Front view of the beam at the output
of the RFQ injection cone
SPIRLA2 LBE LIGHT IONS LINE @ SACLAY
23 SEPTEMBRE 2014 | PAGE 16
EuCARD2/MAX
Successfully commissioned (2 years)
Tuning procedures defined in TraceWin validated.
Beam entrance in RFQ measured at the exact RFQ
position and conform to predictions.
Everything has been performed using “autopilot
tools
SPIRLA2 LBE HEAVY IONS LINE @ LPSC
23 SEPTEMBRE 2014 | PAGE 17
EuCARD2/MAX
Successfully commissioned
The separation power of the optical system has been validated
CONCLUSIONS
23 SEPTEMBRE 2014 | PAGE 18
EuCARD2/MAX
Injectors successfully commissioned
- SILHI @ Saclay / SACM
- LBE Spiral2 (light ions line) @ Saclay / SACM
- LBE Spiral2 (heavy ions line) @ Grenoble / LPSC
Clearly shown the interest of such a tool, especially for operation group.
Perspectives:
Autopilot, development 90% completed, finalized for IPHI commissioning.
Control tower, 75% made, expected this year.
Fight simulator”, probably gave up.
Virtual accelerator has been proposed to SPRILA2 and could be to MYRRHA
project.
“Virtual accelerator is a nice concept but we are also aware that
reality is not a dream world and like an air plane, an ADS
accelerator doesn’t support any approximation”
... The association of the beam dynamics code to an accelerator control system is often mentioned in the literature as a Virtual Accelerator. The structure of a Virtual Accelerator based on the EPICS control system is presented in Fig. 4 and described in detail in References [8] and [9]. The Virtual Accelerator includes a beam dynamics simulation code that is able to run in parallel with the Real Accelerator. ...
... While after several days of manual optimization the transmission achieved 79%, using the Virtual Accelerator it reached 87% within half hour. Most recently the commissioning of the light ions and heavy ions SPIRAL2 injectors have been successfully performed at respectively CEA-Saclay and LPSC-Grenoble using the same Virtual Accelerator control system as for the SILHI injector, validating the tuning procedure defined in TRACEWIN [9]. ...
... Important results were also obtained in 2010-2012 at IRFU/Saclay, where the deuteron/proton ECR source, the transport lines LEBT2 (achromatic analysis section) and LEBC (merging transport and matching line to the RFQ) have been installed in several successive steps (Figure 7). These results were obtained by using intensively the TRACEWIN code for the beam tuning, and by applying the "virtual accelerator concept" explained in [11]. ...
Article
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Heavy Ion and Rare Isotopes Machines, TUO3AB03
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