A5072730104- Particle accelerators and beam dynamics
- Plasma Diagnostics and Applications
- Particle Accelerators and Free-Electron Lasers
- Magnetic confinement fusion research
- Atomic and Molecular Physics
- Superconducting Materials and Applications
- Mass Spectrometry Techniques and Applications
- Particle Detector Development and Performance
- Ion-surface interactions and analysis
- Metal and Thin Film Mechanics
- Electromagnetic Launch and Propulsion Technology
- Nuclear and radioactivity studies
- Muon and positron interactions and applications
- Nuclear Physics and Applications
- Bluetooth and Wireless Communication Technologies
- Chemical and Physical Properties of Materials
- Fusion materials and technologies
- Laser-Plasma Interactions and Diagnostics
- Advanced Data Storage Technologies
- Advanced Electrical Measurement Techniques
- Integrated Circuits and Semiconductor Failure Analysis
- Sensor Technology and Measurement Systems
- Cryptographic Implementations and Security
- Gyrotron and Vacuum Electronics Research
- Electron and X-Ray Spectroscopy Techniques
Rutherford Appleton Laboratory
2014-2024
Science and Technology Facilities Council
2015-2023
UK Research and Innovation
2018-2023
Oak Ridge National Laboratory
2020
University of Oxford
2013-2017
Science Oxford
2014-2015
Saint Thomas - Rutherford Hospital
2013
ISIS Neutron and Muon Source
2012
Imperial College London
2009
An overview of high current (>1 mA) negative hydrogen ion (H–) sources that are currently used on particle accelerators. The understanding how H– ions produced is summarised. Issues relating to caesium usage explored. different ways expressing emittance and beam currents clarified. Source technology naming conventions defined generalised descriptions each source provided. Examples operating outlined, with their status future outlook given. A comparative table
The Front End Test Stand (FETS) under construction at RAL is a demonstrator for front end systems of future high power proton linac. Possible applications include linac upgrade the ISIS spallation neutron source, new sources, accelerator driven sub-critical systems, neutrino factory etc. Designed to deliver 60mA H-minus beam 3MeV with 10% duty factor, FETS consists brightness ion magnetic low energy transport (LEBT), 4-vane 324MHz radio frequency quadrupole, medium (MEBT) containing speed...
The aim of the front end test stand project is to demonstrate that chopped low energy H− beams high quality can be produced. beam line currently consists ion source, a 3 solenoid transport and suite diagnostics. A brief status report radio frequency quadrupole given. This paper details work optimize source performance. new power pulsed discharge supply with greater reliability has been developed allow long term, stable operation at 50 Hz 60 A, 2.2 ms pulse up 100 1.2 ms. existing extraction...
In order to reduce the emittance and increase transported beam current from ISIS Penning-type H(-) ion source, improvements extraction system are required. This source is currently being commissioned on front end test stand at Rutherford Appleton Laboratory, which demands higher energies, currents, smaller emittances. To facilitate this, present geometry requires optimization. paper details experimental simulation studies performed of plasma meniscus possible electrode modifications needed...
The aim of the front end test stand (FETS) project is to demonstrate that chopped low energy beams high quality can be produced. FETS consists a 60 mA Penning Surface Plasma Ion Source, three solenoid beam transport, 3 MeV radio frequency quadrupole, chopper, and comprehensive suite diagnostics. This paper details design initial performance ion source laser profile measurement system. Beam current, profile, emittance measurements are shown for different operating conditions.
A fully detailed 3D thermal model of the ISIS Penning surface plasma source is developed in ANSYS. The proportion discharge power applied to anode and cathode varied until simulation matches operational temperature observations. range possible contact resistances are modelled, which gives an estimation that between 67% 85% goes cathode. Transient models show electrode rise during pulse for a duty cycles. implications these measurements discussed mechanism governing cesium coverage proposed....
A vessel for extraction and source plasma analyses is being used Penning H− ion development at the Rutherford Appleton Laboratory. new set of optical elements including an einzel lens has been installed, which transports over 80 mA beam successfully. Simultaneously, a 2X scaled developed to reduce cathode power density. The now delivering 65 10% duty factor, meeting its design criteria. long-term viability evaluated, so diagnostic devices have installed. pair electrostatic deflector plates...
A vessel for extraction and source plasma analyses (VESPA) is operational at the Rutherford Appleton Laboratory (RAL). This project supports guides overall ion R&D effort ISIS spallation neutron muon facility RAL. The VESPA produces 100 mA of pulsed H− beam, but perveance scans indicate that production-limited voltages above 12 kV unless arc current increased. high resolution optical monochromator used to measure properties using argon as a diagnostic gas. atomic hydrogen temperature...
Abstract Experimental campaigns were undertaken to understand and improve the coupling efficiency of Radio frequency (RF) power into plasma in three accelerator-based ion sources. Different matching circuit mechanical engineering setups used network resistance calculated. The was then measured for a range RF frequencies input gas flows. Coupling efficiencies around 60% using RF-coils mounted external chamber. is improved 80% when coil immersed plasma, allowing closer coupling. As well as...
In order to facilitate the testing of advanced H− ion sources for ISIS and Front End Test Stand (FETS) facilities at Rutherford Appleton Laboratory (RAL), a Vessel Extraction Source Plasma Analyses (VESPA) has been constructed. This will perform first detailed plasma measurements on Penning-type source using emission spectroscopic techniques. addition, 30-year-old extraction optics are re-designed from ground up in fully transport beam. Using multiple beam diagnostics devices, ultimate aim...
Views Icon Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Twitter Facebook Reddit LinkedIn Tools Reprints and Permissions Cite Search Site Citation S. R. Lawrie, D. C. Faircloth, A. P. Letchford, M. Westall, O. Whitehead, T. Wood, J. Pozimski; Redesign of the Analysing Magnet in ISIS H− Penning Ion Source. AIP Conf. Proc. 12 March 2009; 1097 (1): 253–262. https://doi.org/10.1063/1.3112520 Download citation file: Ris (Zotero) Reference Manager EasyBib...
To meet the full 2 ms 50 Hz 60 mA beam requirements for Front End Test Stand (FETS) at Rutherford Appleton Laboratory (RAL), a new caesiated Penning Surface Plasma Source (SPS) has been developed [1] with larger plasma volume 2X linear dimensions of standard ISIS source. This paper outlines design decisions made during development process and details source construction. Improved electrode cooling is required to operate higher duty cycles, this achieved by changing coolant, adding parallel...
A project to design and construct an RF-driven long-lifetime volume production ion source producing 30 mA of H− with 50 Hz repetition rate 1.5% duty factor at 35 keV energy for the ISIS Neutron Muon Source has been started Rutherford Appleton Laboratory. The development new aims replacing caesiated Penning-type surface plasma that served facility since 1980s. is based on recent developments CERN demonstrating in mode less than kW RF-power but lower 0.8 Hz. This paper describes physics status...
Factors limiting the operating lifetime of Compact Surface Plasma Sources (CSPS) are analyzed and possibilities for enhancement considered. Noiseless discharges with lower gas cesium densities produced in experiments a modified discharge cell. With these cells it is possible to increase emission aperture extract same beam low enough emittance from current corresponding source lifetime. A design advanced CSPS production H− average up 20 mA (with pulsed 0.1 A) extrapolated integrated ∼10 hours...
To meet the full 2 ms 50 Hz 60 mA beam requirements for Front End Test Stand (FETS) at Rutherford Appleton Laboratory (RAL), a new cesiated Penning Surface Plasma Source (SPS) has been developed with larger plasma volume 2X (double) linear dimensions of standard ISIS source. This paper outlines development work through preliminary tests and two prototypes. The latest results have demonstrated that operation duty cycle is possible but 'noisy' beam. A 'clean' was obtained lower cycles high cesium flux.
Experiments comparing an internal and external antenna H- source at the Spallation Neutron Source with without cesium revealed key performance differences which provide insight to physics will guide development of RF ISIS Source. power sweeps were taken for each these cases, total charge, electron ratio, extracted per kW are all studied plotted. At around 40 typical hydrogen flow cooling parameters, cesiated sources output 35 mA square beam pulses where uncesiated 15 mA. settings, pulse...
All the Front End Test Stand (FETS) beam requirements have been achieved, but not simultaneously [1]. At 50 Hz repetition rates current droop becomes unacceptable for pulse lengths longer than 1 ms. This is fundamental limitation of present source design. Previous researchers [2] demonstrated that using a physically larger Penning surface plasma should overcome these limitations. The scaled development strategy outlined in this paper. A study time-varying behavior has performed V-UV...
The aim of the Front End Test Stand (FETS) project is to demonstrate that chopped low energy beams high quality can be produced. FETS consists a power Penning Surface Plasma Ion Source, 3 solenoid LEBT, MeV RFQ, chopper and comprehensive suite diagnostics. This paper briefly outlines status project, hardware installation modifications. Results from experiments running H− ion source at 2 ms pulse length are detailed: discharge current varied between 20 A 50 A. repetition rate 12.5 Hz....
The standard 1X ISIS negative Penning surface plasma source has reliably produced an H− beam for operations 35 years. In order to meet the 60 mA, 2 ms, and 50 Hz current duty cycle required front end test stand (Letchford et al., in Proceedings of IPAC2015, Richmond, VA, USA, 2015), a 2X scaled been developed [Faircloth AIP Conf. Proc. 2052, 050004 (2018)]. chamber twice linear dimensions source. This paper investigates comparison between different emission areas (plasma electrode aperture...
The existing ISIS Penning H− source is unable to produce the beam parameters required for front end test stand and so a new, high duty factor, brightness scaled being developed. This paper details first development of an electrically biased aperture plate second, design, simulation, prototype source.
Abstract A novel design framework for Radio Frequency Quadrupoles (RFQs), developed as part of the FETS RFQ, is presented. This integrates several previously disparate steps in RFQs, including beam dynamics design, mechanical electromagnetic, thermal and modelling simulations. Each stage process described detail, various software options reasons final suite selected. Results are given each these steps, describing how affects overall process, with an emphasis on resulting choices RFQ.
The Front End Test Stand (FETS) is located at Rutherford Appleton Laboratory and aims for a high current, fast chopped 3 MeV H– ion beam suitable future power proton accelerators like ISIS upgrade. main components of the front end are Penning source, low energy transport line, an radio-frequency quadrupole (RFQ) medium (MEBT) providing also chopper section rebuncher. FETS in stage commissioning its (LEBT) line consisting three solenoids. LEBT has to current (up 60 mA) 65 keV. This injection...
H− ion source research is being performed at the ISIS spallation neutron and muon facility on a dedicated Vessel for Extraction Source Plasma Analyses (VESPA). The extraction optics system presently used centered combined-function sector dipole magnet. This traps cesium vapor escaping source; mass-separates co-extracted electrons stripped neutrals, weak-focusses highly asymmetric slit-shaped beam. Unfortunately added drift length through magnet under strong space-charge forces means up to...
The ISIS Penning ion source is a pulsed dc discharge surface plasma delivering 55-mA beam of negative hydrogen ions (H <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-</sup> ) in 250-μs pulses to the accelerator for neutron and muon physics at 50-Hz pulse repetition rate. H are extracted from hydrogen-cesium sustained by current-regulated power supply current 50-60 A. exhibits an ignition transient that requires pulselength be prolonged 700 μs...