We report measurements of transverse beam halo in mismatched proton beams in a 52-quadrupole FODO transport channel following the 6.7-MeV LEDA RFQ. Beam profiles in both transverse planes are measured using beam-profile diagnostic devices that consist of a movable carbon filament for measurement of the dense beam core, and scraper plates for the halo measurement. The gradients of the first four quadrupoles can be independently adjusted to mismatch the RFQ output beam into the beam-transport channel.

/pdf/experimental-study-of-proton-beam-halo-induced-by-beam-5cqazlsc3q.pdf

Experimental study of proton-beam halo induced by beam mismatch in LEDA

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

The LEDA 75 keV injector and 6.7 MeV RFQ have been tested with pulsed and cw proton beam currents up to 100 mA. Several LINAC2000 papers give the results of those measurements. A follow-on experiment, to intentionally introduce and measure beam halo on the RFQ output beam, is reported in several papers at this conference (PAC2001). In this paper we summarize the LEDA RFQ commissioning results and the beam-halo measurements and we discuss future test plans for this high-current, high-average-power RF structures test bed.

/pdf/low-energy-demonstration-accelerator-leda-test-results-and-3fbtqj71zp.pdf

Low-Energy Demonstration Accelerator (LEDA) test results and plans

An experimental effort has been undertaken to investigate the production of halo particles in a proton beam having significant space charge forces. The LEDA RFQ was used to inject a pulsed 6.7 MeV 15-75 mA beam into a linear FODO channel. Four matching quads at the input of this 52-quadrupole transport line were used to generate specific mismatch oscillations, believed to be a key mechanism in the generation of beam halo. A suite of diagnostics that provide beam profile measurements over a wide dynamic range enabled a detailed comparison of measurements with theoretical models.

/pdf/measurements-of-halo-generation-for-a-proton-beam-in-a-fodo-18vosy198n.pdf

Measurements of halo generation for a proton beam in a FODO channel

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

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

R.B. Shurter

Papers

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

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