A 52 quadrupole-magnet FODO lattice has been assembled and operated at the Los Alamos National Laboratory. The purpose of this lattice is to provide a platform to measure the resulting beam halo as the first four magnets of the lattice produce various mismatch conditions. These data are then compared with particle simulations so that halo formation mechanisms may be better understood. The lattice is appended to the LEDA 6.7-MeV radiofrequency quadrupole (RFQ) and is followed by a short high-energy beam transport (HEBT) that safely dumps the beam into a 670-kW beam stop. Beam diagnostic instruments are interspersed within the lattice and HEBT. The primary instruments for measuring the beam halo are nine interceptive devices that acquire the beam's horizontal and vertical projected particle density distributions out to an approximate 10/sup 5/:1 dynamic range. These distributions are acquired using both traditional wire scanners and water-cooled graphite scraping devices. The lattice and HEBT instrumentation set also includes position, bunched-beam current, pulsed current, and beam loss measurements. This paper briefly describes and details the operation of each instrument compares measured data from the different types of instruments, and refers to other detailed papers.

/pdf/experience-with-the-low-energy-demonstration-accelerator-4cdfv40dwo.pdf

Experience with the low energy demonstration accelerator (LEDA) halo experiment beam instrumentation

Programmable analog signal conditioning circuits can be programmed in the field to permit their use in several applications with a variety of sensors with different output signal characteristics. The digital programming of the gain and dc level shift of a conditioning circuit can affect the measurement resolution and cause a reduction in the range of the measuring system in which it is employed. For a specified maximum acceptable loss in the measurement resolution, a procedure for defining and employing the programming values that guarantees the full measurement range is proposed. The proposed methodology takes into account practical implementation considerations and can be employed for designing either discrete or integrated circuits.

Designing a programmable analog signal conditioning circuit without loss of measurement range

This paper describes a project designed by a group of second year mechatronics undergraduates (MechUGs) at Monash University Malaysia. A rapid prototype design for a XY plotting mechanism integrated with a CREATIVE webcam for the purpose of image acquisition and subsequent processing was developed. Motion control of this XY mechanism with an inexpensive machine vision system was developed. LabVIEW, IMAQ Vision softwares and motion controller hardware PCI-7344 were presented to a group of students for the first time. These five MechUGs were taking a problem based learning module that required them to complete a given mechatronically oriented project in only a short span of 13 weeks. The fundamental concept behind this XY plotting mechanism was to harness the precision of VEXTA stepper motors in order to accurately plot pre-programmed shapes or alternatively draw contours of images acquired from the webcam. Image acquisition and processing techniques such as thresholding, contour extraction etc. were introduced and utilized by these MechUGs. This paper describes how these MechUGs designed and constructed this prototype system. This paper also illustrates the significant enhancement of knowledge gained and hands-on skills by these undergraduates in this problem based learning experience. The Flexmotion functions in LabVIEW were utilized for the purpose of interacting with this 4 axes motion controller card (PCI-7344) to control a three stepper motors system. Additionally coordinated image acquisition, processing and motion control plotting examples were presented in this work for further illustration

Rapid Prototyping Design and Implementation of a Motion Control IntegratedWith an Inexpensive Machine Vision System

Within the halo experiment presently being conducted at the Low Energy Demonstration Accelerator (LEDA) at Los Alamos National Laboratory, specific beam instruments that acquire horizontally and vertically projected particle-density distributions out to approximately 10/sup 5/:1 dynamic range are located throughout the 52-magnet halo lattice. We measure the core of the distributions using traditional wire scanners, and the tails of the distribution using water-cooled graphite scraping devices. The wire scanner and halo scrapers are mounted on the same moving frame whose location is controlled with stepper motors. A sequence within the Experimental Physics and Industrial Control System (EPICS) software communicates with a National Instruments LabVIEW virtual instrument to control the motion and location of the scanner/scraper assembly. Secondary electrons from the wire scanner 0.033-mm carbon wire and protons impinging on the scraper are both detected with a lossy-integrator electronic circuit. Algorithms implemented within EPICS and in Research System's Interactive Data Language subroutines analyze and plot the acquired distributions. This paper describes this beam profile instrument, describes our experience with its operation, compares acquired profile data with simulation, and refers to other detailed papers.

/pdf/beam-profile-instrumentation-for-beam-halo-measurement-2huocdlghj.pdf

Beam-profile instrumentation for beam-halo measurement: overall description and operation

A new diagnostic has been designed and commissioned that measures the profile of the beam in the halo channel of the Low Energy Demonstration Accelerator at the Los Alamos National Laboratory. This paper describes the algorithms written to analyze the data from that diagnostic, a combined wire scanner and halo scraper. These algorithms determine the safe insertions limit of the scrapers, spatially differentiate the scraper signal, amalgamate the wire scanner data with the differentiated scraper data, determine when both the core and combined distributions rise above the noise floor, and compute the moments of the combined distribution. Results of applying the algorithms to data acquired during experiments matching the beam into the halo channel are presented.

/pdf/analysis-of-data-from-the-leda-wire-scanner-halo-scraper-460pujow0w.pdf

Analysis of data from the LEDA wire scanner/halo scraper

The halo experiment presently being conducted at the Low Energy Demonstration Accelerator (LEDA) at Los Alamos National Laboratory utilizes a generally traditional wire scanner for measurement of the beam core profile and a graphite scraper for measurement of the tails of the beam distribution. A lossy integrator is used to detect the replacement charge flowing to the wire and scraper. Independent programmable dc-bias voltages are applied to the wire and the scraper through the analog electronic interface to optimize the charge capture from the two sensors. A programmable guard voltage is applied to isolate the scraper from the resistivity of the cooling system. A programmable gain provides a total dynamic range in the analog electronics of greater than about one part in 10/sup 6/. The analog signal is digitized to 14 bits plus sign, and the equivalent input noise is nominally 30 fC.

/pdf/beam-profile-wire-scanner-halo-scraper-sensor-analog-2z3qovmo5o.pdf

Beam profile wire-scanner/halo-scraper sensor analog interface electronics

The Low-Energy Demonstration Accelerator (LEDA), designed and built at the Los Alamos National Laboratory, is part of the Accelerator Production of Tritium (APT) program and provides a platform for measuring high-power proton beam-halo formation. Beam Position Monitors (BPMs) are placed along the FODO lattice and the HEBT. The BPM systems employing log-ratio processor electronics have recently been upgraded for all fifteen BPMs along the accelerator. Two types of calibration are now used. The first corrects for errors within the electronics module and the log-amp transfer function non-conformity. The second is a single-point routine used to correct for cable plant attenuation differences. This paper also covers the new switching systems used for various system calibration modes as well as various results from LEDA beam runs. New switching algorithms were implemented in order to remove sensitive electronic switches from within the beam tunnel radiation environment. Attention will be paid to the calibration algorithms and switching system interactions, and how well they work in practice.

/pdf/upgrade-to-initial-bpm-electronics-module-and-beamline-13h00nj5n7.pdf

Upgrade to initial BPM electronics module and beamline components for calibration of the LEDA beam position measurements

The Low-Energy Demonstration Accelerator (LEDA), designed and built at the Los Alamos National Laboratory, is part of the Accelerator Production of Tritium (APT) program and provides a platform for measuring high-power proton beam-halo formation. The technique used for measuring the beam halo employs nine combination Wire Scanner and Halo Scraper (WS/HS) devices. This paper focuses on the experience gained in the use of National Instrument (NI) LabVIEW VIs and motion controllers, and Compumotor electronic drive units and motors. The base configuration couples a Compumotor motor driven by a Parker-Hannifin Gemini GT Drive unit. The drive unit is controlled by a NI PXI-7344 controller card, which in turn is controlled by a PC running custom built NI LabVIEW VIs. The function of the control VI's is to interpret instructions from the main control system, the Experimental Physics and Industrial Control System (EPICS), and carry out the corresponding motion commands. The main control VI has to run all nineteen WS/HS motor axes used in the accelerator. A basic discussion of the main accelerator control system, EPICs which is hosted on a VXI platform, and its interface with the PC based LabVIEW motion control software is included.

/pdf/design-and-experience-with-the-ws-hs-assembly-movement-using-esqgez3jhb.pdf

Design and experience with the WS/HS assembly movement using LabVIEW VIs, National Instrument motion controllers, and compumotor electronic drive units and motors

The Los Alamos Neutron Science Center (LANSCE) is installing two beam lines to both improve operational tuning and provide new capabilities. The Isotope Production Facility (IFF) will provide isotopes for medical purposes by using the H/sup +/ beam spur at 100 MeV and the Switchyard Kicker Upgrade (SYK) will allow the LANSCE 800-MeV H/sup -/ beam to be rapidly switched between various beam lines within the facility. The beam position instrumentation for both of these beam lines uses a microstripline beam position monitor (BPM) with a 50-mm or 75-mm radius. The cable plant is unique in that it unambiguously verifies the operation of the complete position instrumentation. The processing electronics use a log ratio technique with error correction such that it has a dynamic range of -12 dBm to -85 dBm with errors less than 0.15 dB within this range. This paper will describe the primary components of these measurement systems and provide initial data of their operation.

/pdf/beam-position-measurements-at-los-alamos-isotope-production-35ra4i7187.pdf

D. Barr

Papers

Beam profile wire-scanner/halo-scraper sensor analog interface electronics

Upgrade to initial BPM electronics module and beamline components for calibration of the LEDA beam position measurements

Design and experience with the WS/HS assembly movement using LabVIEW VIs, National Instrument motion controllers, and compumotor electronic drive units and motors

Beam position measurements at Los Alamos: Isotope Production Facility and Switchyard Kicker Upgrade