Upgrading the Data Acquisition and Control System of the LANSCE LINAC
Los Alamos National Laboratory LANL is in the process of upgrading the control system for the Los Alamos Neutron Science Center (LANSCE) linear accelerator. The 38 year-old data acquisition and control equipment is being replaced with COTS hardware. An overview of the current system requirements and how the National Instruments cRIO system meets these requirements will be given, as well as an update on the installation and operation of a prototype system in the LANSCE LINAC.
LANSCE-R WIRE-SCANNER SYSTEM
The National Instruments cRIO platform is used for the new LANSCE-R wire-scanner systems. All wire-scanner electronics are integrated into a single BiRa BiRIO 4U cRIO chassis specifically designed for the cRIO crate and all interface electronics. The BiRIO chassis, actuator and LabVIEW VIs provide a complete wire-scanner system integrated with EPICS. The new wire-scanner chassis includes an 8-slot cRIO crate with Virtex-5 LX 110 FPGA and Power-PC real-time controller, the LANL-developed cRIO 2-axis wire-sensor analog interface module (AFE), NI-9222 cRIO 4-channel 16-bit digitizer, cRIO resolver demodulator, cRIO event receiver, front-panel touch panel display, motor driver, and all necessary software, interface wiring, connectors and ancillary components. This wirescanner system provides a complete, turn-key, 2-axis wire-scanner system including 2-channel low-noise sensewire interface with variable DC wire bias and wireintegrity monitor, 16-bit signal digitizers, actuator motor drive and control, actuator position sensing, limit-switch interfaces, event receiver, LabVIEW and EPICS interface, and both remote operation and full stand-alone operation using the touch panel.
LANSCE-R WIRE-SCANNER ANALOG FRONTEND ELECTRONICS (AFE)
A new AFE is being developed for the new LANSCE-R wire-scanner systems. The new AFE is implemented in a National Instruments cRIO module installed a BiRa 4U BiRIO cRIO chassis specifically designed to accommodate the cRIO crate and all the wire-scanner interface, control and motor-drive electronics. A single AFE module provides interface to both X and Y wire sensors using true DC coupled transimpedance amplifiers providing collection of the wire charge signals, real-time wire integrity verification using the normal dataacquisition system, and wire bias of 0V to +/-50V. The AFE system is designed to accommodate comparatively long macropulses (>1ms) with high PRF (>120Hz) without the need to provide timing signals. The basic AFE bandwidth is flat from true DC to 50kHz with a true first-order pole at 50kHz. Numeric integration in the cRIO system provides real-time pulse-to-pulse numeric integration of the AFE signal to compute the total charge collected in each macropulse. This method of charge collection eliminates the need to provide synchronization signals to the wire-scanner AFE while providing the capability to accurately record the charge from long macropulses at high PRF.
CLOSED LOOP WIRE SCANNER ACTUATOR CONTROL FOR LANSCE ACCELERATOR BEAM PROFILE MEASUREMENTS
The design and test of a new beam-profile wire-scanner actuator for the LANSCE(Los Alamos Neutron Science Center) 800-MeV proton linear accelerator is described. Previous actuator implementations use open-loop stepper-motor control for position indexing. A fixed-frequency, fixed-duration pulse train is sent to the stepper motor driving the linear actuator. This has led to either uncertainties in position due to mechanical resonances and electrical noise or slowing down actuator operation.. A real-time, closed loop control system is being developed and tested for more repeatable and accurate positioning of beam sense wires. The use of real-time controller allows one to generate a velocity profile for precise, resonance-free wire position indexing. High radiation levels in the beam tunnel, dictate the use of an electro-magnetic resolver, typically, used in servo applications, as the position feedback element. Since the resolver is an inherently analog device, sophisticated digital signal processing is required to generate and interpret the waveforms that the feedback mechanism needs for positioning. All of the electronic and computational duties are handled in one the National Instruments compact RIO real-time chassis with a Field-Programmable Gate Array (FPGA).
MODBUS/TCP CONTROLLER FOR THE POWER SUPPLIES IN ALS BTS BEAM LINE
The development, testing and commissioning of a self-contained power supply controller for four 100 KW power supplies for the upgraded Booster to Storage Ring (BTS) beam line at the Advanced Light Source( ALS) at the Lawrence Berkeley Laboratory, is presented. The power supply controller is a 3U high, rack-mount chassis that contains the regulation control-loop amplifiers, 16-bit DAC with microcontroller and a micro PLC (Programmable Logic Controller) for power-supply state-machine control. Local control is achieved via push-buttons and a color LCD touch screen. Remote control is mediated via micro PLC using embedded Modbus/TCP. Using a unique, data logging system, the operational parameters of the regulation loop can be safely monitored and recorded while the system is running at full power. The entire design is based on optimum reliability, safety and ease of troubleshooting and repair. A modular design for key control components, allows the power supply to operate in a nominal mode, even if one or two ancillary internal modules fail. This allows for continued beam operation until it is convenient to service the unit, keeping beam availability as high as possible.
FULL REAL-TIME TEMPERATURE MAPPING SYSTEM FOR 1.3 GHZ 9-CELL CAVITIES
The mapping of outer-wall temperatures during the vertical test of a superconducting radio-frequency (SRF) cavity has been one of the most successful tools in studying the cavity loss mechanisms. However, due to the excessive number of sensors needed, no fixed-type temperature mapping (T-mapping) system that covers all cells has been built for 9-cell cavities. With the consensus that T-mapping analysis is needed in order to improve the yield of high-gradient cavities, a system with a reduced data acquisition time and increased temperature sensitivity, compared to rotating-arm systems, has been developed at LANL. The system consists of 4608 100-ohm 1/8W Allen-Bradley resistors placed azimuthally every 10 degrees, a similar number of other resistors and diodes that implement the switching scheme, and data acquisition codes written in LabView. The details of the system and first results are presented and discussed.
DIGITAL CONTROL INTERFACE FOR BIPOLAR CORRECTOR POWER SUPPLIES FOR LCLS
We detail the development, testing and commissioning of a single-board digital interface for modular bipolar corrector magnet power supplies to be installed at the Linac Coherent Light Source (LCLS) at the Stanford Linear Accelerator (SLAC). The sixteen-channel VME-form-factor board replaces the passive control-interface board in the MCOR (Magnet Corrector) Chassis. The board is a self-contained system with both serial and Ethernet connectivity intended for use with an EPICS accelerator control system IOC, however, the ASCII protocol allows generic computer control. The interface card contains 16 independent ADC and DAC channels, each with 16 bits of resolution. Additionally, the interlock, fault, reset and digital control lines are remotely controllable via either the serial or Ethernet connections. The design has been planned so that a mini-IOC can be included on board for direct Channel Access connectivity.
COMPACT PCI/PXI BASED HIGH VOLTAGE CARDS
High voltage power modules find uses in many applications like the Photo multiplier Tubes (PMT), Ionization chambers, CRT systems testing, high voltage biasing for Avalanche Photodiodes, Photo detectors, X-ray tubes, Pulse generators which are used in radars, lasers, EMC testing and other imaging applications. Providing high voltage, to these applications, which can be remotely controlled in a small, confined area, is a problem many laboratories around the world face. The LV and the HV series of high voltage systems present experimenters with voltages ranging from several hundreds upto +/- 5kV in a rugged CompactPCI / PXI chassis, running National Instruments LabView. The CompactPCI architecture offers modularity, tight integration and low cost. Apart from that, the deterministic and real time nature of the operating system (LabView) also allows these modules to be remotely controlled and monitored over the Ethernet. The high voltage cards can be easily custom tailored to a particular voltage and current requirement.
MULTI-CHANNEL MAGNET POWER-SUPPLY RAMP CONTROLLER FOR THE IUCEEM ALPHA SYNCHROTRON/STORAGE RING WITH CHANNEL ACCESS
A four-channel magnet-power-supply ramp controller has been designed and deployed at the new ALPHA (Advanced Electron Photon Facility) at the Indiana University Center for Exploration of Energy and Matter (IUCEEM). The first application is a power-supply controller. For all practical purposes, the system is a versatile arbitrary voltage-waveform-generator with full DAQ (data acquisition) capabilities that can be used in a variety of beam instrumentation settings. The real-time controller can generate four arbitrary independently-triggerable ramp profiles. A normalized wave-form vector is encoded as a Process Variable array and is uploaded and stored by the real-time controller as required. Each ramp array element is clocked out to a 16-bit DAC (Digital to Analog Converter) via a DMA FIFO and built-in FPGA. The duration of the waveform is programmable with a minimum time resolution of 20 µsec between profile values. Four bipolar DACs have an output range of +/- 10V. Eight digital I/O control bits are allocated for each control channel. Typically, these bits are used to monitor and control the power-supply operational state. The control-system interface uses the EPICS Channel-Access server accessible on Labview RT 2009.