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Batavia, IL, United States

Dudnikov V.,Muons, Inc.
Review of Scientific Instruments | Year: 2012

The cesiation effect, a significant enhancement of negative ion emission from a gas discharge with decrease of co-extracted electron current below negative ion current, was observed for the first time on July 1, 1971 by placing into the discharge a compound with 1 mg of cesium. Subsequent developments of surface plasma sources (SPS) for highly efficient negative ion production caused by the interaction of plasma particles with electrodes on which the adsorbed cesium reduced the surface work function are described. In the last 40 years, the intensity of negative ion beams has increased by cesiation up to 10 4 times from 3 mA to tens of amperes. Here, the main attention is concentrated on earlier SPS developments because recent results are well known and widely available. © 2012 American Institute of Physics.


Grant
Agency: Department of Energy | Branch: | Program: SBIR | Phase: Phase I | Award Amount: 150.00K | Year: 2015

Battery-powered compact, portable sources of gamma rays with energies between 1 MeV and 6 MeV and with variable duty cycles are needed for a variety of applications, from homeland security to a broad range of industrial and medical applications. Radioactive sources, although compact, are not tunable and are hazardous even when not being used. Typical industrial electron accelerators that provide gamma rays of the required energy are not compact or portable, nor can they operate on batteries. We propose a novel temperature-stabilized solid-state permanent-magnet microtron electron accelerator to provide a lightweight gamma-ray source with outstanding performance parameters and flexibility. The electrons are accelerated by a small RF cavity powered by a highly-efficient magnetron power source. Compactness and portability are achieved by using a magnet that does not need coils, power, or cooling, and using an efficient accelerating system that minimizes the need for RF power and cooling. The classical microtron design that we propose has a built-in vacuum chamber that eliminates a reliability issue seen in betatron gamma ray sources. A prototype portable microtron will be produced in Phase II. In Phase I, computations and simulations will be done to demonstrate accelerator performance and to verify that all requirements can be met. In addition, a complete conceptual design of a prototype unit will be produced, including the electrical, electronic, mechanical, and magnetic components. The design will utilize commercially available components from the US. Commercial applications of compact gamma ray sources include detection of fissile materials, observation of flaws in industrial components, discovery of flaws and weaknesses in bridges and other construction structures, medical scanning, oil exploration and others.


Grant
Agency: Department of Energy | Branch: | Program: STTR | Phase: Phase II | Award Amount: 750.00K | Year: 2010

Spallation neutron source user facilities require reliable, intense beams of protons. The technique of H- charge exchange injection into a storage ring or synchrotron has the potential to provide the needed beam currents. However, the facility operation is limited by the performance of H- ion sources with currents, brightness, reliability and availability that could still be improved. In this project we will develop an H- source design which will synthesize the most important developments in the field of negative ion sources to provide high current, small emittance, good lifetime, and high reliability, by improving power efficiency. Several versions of new plasma generators with different antennas and magnetic field configurations were designed, built and tested on a test stand, where a factor of 5 improvements in useful plasma flux generation was demonstrated. These plasma generators are compatible with the SNS RF H- Source and were tested on the SNS Test Stand. Stable H- beam production up to 56 kW RF power was demonstrated with a beam current up to 67 mA using a prototype saddle antenna. An H- ion generation efficiency of 1.6 mA/kW was also demonstrated. An advanced version of an RF H-source with an improved plasma generator (developed in Phase I) will be developed in full scale with the goal of having a long operational lifetime with improved beam parameters (pulsed H- beam current up to 70 mA, average H- beam current up to 5 mA with pulsed power


Grant
Agency: Department of Energy | Branch: | Program: STTR | Phase: Phase II | Award Amount: 750.00K | Year: 2010

A superconducting RF (SRF) power coupler capable of handling 500 kW CW RF power at 750 MHz is required for present and future storage rings and linacs. There are over 35 coupler designs for SRF cavities ranging in frequency from 325 to 1500 MHz. Coupler windows vary from cylinders to cones to disks and RF power couplers will always be limited by the ability of ceramic windows and their matching systems to withstand the stresses due to non-uniform heating from dielectric and wall losses, multipactor, and mechanical flexure. We propose a novel robust co-axial SRF coupler design which uses two windows manufactured with compression ring technology and no matching elements in the coax line. This technology will allow the use of high thermally conductive materials for cryogenic windows because the braze joint will be in compression. In Phase II a scaled down version of the 500kW CW double window assembly will be built and tested at high power in order to finalize the design for the full size version. A compressed co-axial window was designed and fabricated using standard ceramics. The mechanical design incorporated several critical process elements that made sure other materials could be used without concern for metalizing issues. Low power tests confirmed the broadband match characteristics of a double window design. Window materials will be used in the assembly processes ranging from soft boron nitride to lossy aluminum nitride and sapphire. A scaled down version of the ultimate double window design for 500kW CW at 750 MHz will be built and stress tested at cryogenic temperatures as well as room temperature with varying pressures and gases. As a result of these comprehensive tests, a design scaled up to full power CW can be reliably produced. Commercial Applications and other Benefits: Double-window, coaxial input couplers or coaxial pressure barriers have high power CW applications ranging from RF guns for injectors to high power magnetron sputtering systems. Single half-wavelength coaxial windows built with our compression technology will handle significantly more power than standard windows.


Grant
Agency: Department of Energy | Branch: | Program: SBIR | Phase: Phase II | Award Amount: 750.00K | Year: 2010

Intense muon beams have many potential commercial and scientific applications, ranging from low-energy investigations of the basic properties of matter using spin resonance to large energy-frontier muon colliders. However, muons originate from a tertiary process that produces a diffuse swarm. To make useful beams, the swarm must be rapidly captured and cooled before the muons decay. General statement of how this problem is being addressed. This is the overall objective of the combined Phase I and Phase II projects. A promising new concept for the collection and cooling of muon beams to increase their intensity and reduce their emittances is being investigated, namely, the use of a nearly isochronous helical cooling channel (HCC) to facilitate capture of the muons into RF bunches. The muon beam could then be cooled quickly and coalesced efficiently to optimize the luminosity of a muon collider, or could provide compressed muon beams for other applications. Optimal ways to integrate such a subsystem into the rest of a muon collection and cooling system, for collider and other applications, will be developed by analysis and simulation. The application of quasi-isochronous helical cooling channels (QIHCC) for RF capture of muon beams was developed. Innovative design concepts for a channel incorporating straight solenoids, a matching section, and an HCC, including RF and absorber, were developed, and its subsystems were simulated. Additionally, a procedure that uses an HCC to combine bunches for a muon collider was invented and simulated. The Phase II research will refine the QIHCC by continuing to develop the design concepts. Difficult design aspects such as matching sections between subsystems and intensity-dependent effects will be addressed. The bunch recombination procedure will be developed into a complete design with 3-D simulations. Commercial applications and other benefits: Bright muon beams are needed for many commercial and scientific reasons. Potential commercial applications include the use of muon beams to screen cargo containers for homeland security, low-dose radiography, and muon catalyzed fusion. Scientific uses include low energy beams for rare process searches, muon spin resonance applications, muon beams for neutrino factories, and muon colliders as Higgs factories or energy-frontier discovery machines.

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