Space-charge limits for linear accelerators

Maschke, A.

doi:10.2172/5914736

Cited by 14 publications

(8 citation statements)

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“…LBNL and Cornell developed a new ion beam architecture based on microelectromechanical systems (MEMS) technology that utilizes an array of "beamlets"which will be scalable up to hundreds or thousands of beamlets per 4 to 12 inch wafer, and enabling very high system-level current density as the array of parallel beamlets deliver high ion flux even as no individual beamlet approaches space charge limits. The design is based upon the MEQALAQ accelerator design developed at Brookhaven National Lab in the 1980's, but the addition of MEMS technology offers a path to mass manufacturability, and simplicity and scalability in the integration of RF with MEMS wafers [69]. The team was able to demonstrate proof of concept for the MEMS accelerator with a prototype compact accelerator fabricated from PCB board.…”

Section: Exploratory Concepts Lawrence Berkeley National Laboratomentioning

confidence: 99%

Retrospective of the ARPA-E ALPHA Fusion Program

et al. 2019

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This paper provides a retrospective of the ALPHA (Accelerating Low-cost Plasma Heating and Assembly) fusion program of the Advanced Research Projects Agency-Energy (ARPA-E) of the U.S. Department of Energy. ALPHA's objective was to catalyze research and development efforts to enable substantially lower-cost pathways to economical fusion power. To do this in a targeted, focused program, ALPHA focused on advancing the science and technology of pulsed, intermediate-density fusion approaches, including magneto-inertial fusion and Z-pinch variants, that have the potential to scale to commercially viable fusion power plants. The paper includes a discussion of the origins and framing of the ALPHA program, a summary of project status and outcomes, a description of associated technology-transition activities, and thoughts on a potential follow-on ARPA-E fusion program. Introduction:In 2014 the Advanced Research Projects Agency-Energy (ARPA-E) of the U.S. Department of Energy (DOE) launched a new research program on low-cost approaches to fusion-energy development [1]. The "Accelerating Low-Cost Plasma Heating and Assembly" (ALPHA) program set out to enable more rapid progress towards fusion energy by establishing a wider range of technological options that could be pursued with smaller, lower-cost experiments, short development and construction times, and high experimental throughput. Mainstream fusion research generally refers to magnetically or inertially confined fusion, both of which require expensive facilities for reasons briefly described below and explored in more detail in several books[2] [3]. ALPHA focused on magneto-inertial fusion (MIF), a class of pulsed fusion approaches with fuel densities in between those of magnetic and inertial fusion[4], [5] [6]. This paper presents a brief background on the origins of the ALPHA program, the results achieved by ALPHA-funded teams, and a look ahead to potential next steps for low-cost fusion development. OriginsARPA-E's mission is to develop transformational new energy technologies [7]. While DOE has pursued fusion energy as a potentially transformational opportunity for decades, ARPA-E had not supported any work in fusion prior to the ALPHA program. This was in part due to a perception that fusion was inherently the realm of "big science" and that ARPA-E, which runs relatively small, targeted, short-term programs across a wide spectrum of energy technologies-did not have a role to play in that development. In launching ALPHA, ARPA-E sought to change this dynamic and bring new players into the field -both in terms of the kinds of teams doing fusion development (e.g., smaller groups and private startups), and in terms of the sources of funding (e.g., private investors). The ALPHA program

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Section: Exploratory Concepts Lawrence Berkeley National Laboratomentioning

confidence: 99%

Retrospective of the ARPA-E ALPHA Fusion Program

et al. 2019

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“…Hence, it is difficult to achieve high current-densities in small footprint single beam accelerators. In this paper, a Multiple Electrostatic Quadrupole Array Linear Accelerator (MEQALAC) concept has been adopted to reduce the space-charge issues and improve the effective current density by relying on multiple beamlets [6]. Furthermore, this approach lends itself to reduce the total power required during acceleration and focusing [6].…”

Section: Introductionmentioning

confidence: 99%

Demonstration of waferscale voltage amplifier and electrostatic quadrupole focusing array for compact linear accelerators

Vinayakumar

Ardanuç

et al. 2019

Journal of Applied Physics

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Compact linear accelerators with beam energies in the keV to MeV range have applications in medicine, neutron/X-ray generation, surface modifications, etc. The size, weight and power of existing accelerators precludes them from mass availability in portable formats. This paper presents a specific implementation of an ion accelerator architecture based on planar wafers with accelerating and focusing sections. Our low cost approach allows the control of the final ion beam energy with potential applications, for example, for accelerator-based ion implantation. In this paper, we demonstrate two important waferscale modules required to build a linear particle accelerator these include (1) on-wafer voltage amplification for beam acceleration using Inductor-Capacitor (LC) resonators and (2) waferscale electrostatic quadrupole arrays (ESQA) to re-focus the ion beams during transport. On-board LC resonators were developed using a Printed Circuit Board (PCB) fabrication processes to implement an LC element resonant at ~16.6 MHz with a quality factor of 25. An energy gain of ~250 electron volts was observed using a two wafer acceleration unit with an argon ion beam with 6.5 keV initial energy. A 3×3 ESQA was fabricated on a glass wafer with metal electrodes formed by depositing copper metal around the beam apertures. The ESQA was used to focus and defocus an argon ion beam demonstrating a field gradient of ~500 V over a gap of ~250 microns.

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“…Figure 1 shows the MEQALAC concept. The key components required to develop a MEQALAC are an ion source, an ion extraction unit, focusing elements and accelerating stages [1][2][3][4]. Focusing elements are used to keep the beam in-line with the main direction of motion as self-repulsion of charged particles in the beam increases the beam diameter.…”

Section: Introductionmentioning

confidence: 99%

“…This device is a key enabler for a waferbased accelerator architecture that lends itself to orders-ofmagnitude reduction in cost, volume and weight of charged particle accelerators. ESQs are a key building block in developing compact Multiple Electrostatic Quadrupole Array Linear Accelerator (MEQALAC) [1]. In a MEQALAC electrostatic forces are used to focus ions, and electrostatic field scaling permits high beam current densities by decreasing the beam aperture size for a given peak electric field set by breakdown limitations.…”

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confidence: 99%

Waferscale electrostatic quadrupole array for multiple ION beam manipulation

Vinayakumar

Persaud

et al. 2018

2018 IEEE Micro Electro Mechanical Systems (MEMS)

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We report on the first through-wafer silicon-based Electrostatic Quadrupole Array (ESQA) to focus high energy ion beams. This device is a key enabler for a waferbased accelerator architecture that lends itself to orders-ofmagnitude reduction in cost, volume and weight of charged particle accelerators. ESQs are a key building block in developing compact Multiple Electrostatic Quadrupole Array Linear Accelerator (MEQALAC) [1]. In a MEQALAC electrostatic forces are used to focus ions, and electrostatic field scaling permits high beam current densities by decreasing the beam aperture size for a given peak electric field set by breakdown limitations. Using multiple parallel beams, each totaling to an area A, can result in higher total beam current compared to a single aperture beam of the same area. Smaller dimensions also allow for higher focusing electric field gradients and therefore higher average beam current density. Here we demonstrate that Deep Reactive Ion Etching (DRIE) micromachined pillar electrodes, electrically isolated by silicon-nitride thin films enable higher performance ESQA with waferscale scalability. The fabricated ESQA are able to hold up to1 kV in air. A 3×3 array of 12 keV argon ion beams are focused in a wafer accelerator unit cell to pave the way for multiple wafer accelerator.

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Space-charge limits for linear accelerators

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Cited by 14 publications

References 0 publications

Retrospective of the ARPA-E ALPHA Fusion Program

Retrospective of the ARPA-E ALPHA Fusion Program

Demonstration of waferscale voltage amplifier and electrostatic quadrupole focusing array for compact linear accelerators

Waferscale electrostatic quadrupole array for multiple ION beam manipulation

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