Draft:Accelerator Contron System

An Accelerator Control System (ACS) is a computer environment that allows remote access to the accelerator hardware with a lot of different functionality to satisfy the requirements of several different user groups.

The users are: Accelerator Physicists, Operators (technical Staff, in most cases no theoretical background knowledge), System Experts (Vacuum Experts, RF Group, etc.), Experiment Users (not necessarily Physicists), Sponsors (Politicians, General Public, etc.), Control System Specialists (Computer Scientists, Physicists, Nerds).

An Accelerator Control System:
 * Controls the accelerator (Source, Magnets, RF);
 * Provides diagnostics information (BPMs, Cameras);
 * Monitors environment (Vacuum, Temperature);
 * Runs feedback programs for beam parameters (e.g. orbit feedback);
 * Makes “the machine” running and controllable (reliable, with good performance, flexible, economically safe).

An Accelerator Control System actually controls thousands of devices. For example, in the case of a Swiss Light Source (SLS at PSI), there are 200 computers, 600 magnets (+power supplies), 300 vacuum pumps, 9 cavity structures, 150 beam position monitors, and 21 beamlines (together) with 300 computers, 10 undulator magnets, and more than 1200 motors to control. All the components are distributed along a storage ring with 130 m diameter: i.e., 50 km power cable and more than 500 km signal cable. This means that an Accelerator Control System has to make the accelerator controllable from a distant Control Room (may be a kilometer away) using Computer Systems. Moreover, some experiments are controlled remotely from all over the world.

Some examples of applications and programs needed to run an accelerator:
 * Device Control Panels
 * Feedback Systems (e.g. orbit feedback, filling pattern feedback)
 * Archiving and Data Acquisition Systems (Storage)
 * Scan tools for experiments and measurements
 * Conditioning tools for RF components
 * Simulations and comparisons with real accelerator
 * Alarm handling and machine protection.

There are 4 possible architectures of an Accelerator Control System: One practical solution is to mix between some or all of those architectures.
 * 1) Centralized: Single point of failure.
 * 2) Columns: No exchange of information between different systems.
 * 3) Network (Peer‐to‐peer): Can be difficult to maintain if an addition has to be added to all other systems.
 * 4) Layer: Can be difficult to find out where information came from.

Accelerator Control System examples: EPICS, TANGO, DOOCS, ACS, SCADA, WINCCOA.