Measured and theoretical characterization of the RF properties of stacked, high-gradient insulator material

Houck, T.; Caporaso, G.J.; Shang, C. C.; Sampayan, S.; Molau, N.E.; Krogh, M.

doi:10.1109/pac.1997.751296

Cited by 10 publications

(3 citation statements)

References 3 publications

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“…This negative charge repelled electrons upwards away from the insulator surface, inhibiting the avalanche growth for this geometry. Preliminary electromagnetic experimental studies of the High Gradient Insulator (HGI) led to several general observations regarding their characteristics when placed in the opening of a resonant cavity, specifically a resonant cavity representative of an induction accelerator module gap [11,12].…”

Section: B Insulator Scalingmentioning

confidence: 99%

Advanced accelerator theory development

Sampayan¹,

Houck²,

Poole³

et al. 1998

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A new accelerator technology, the dielectric wall accelerator (DWA), is potentially an ultra compact accelerator/pulsed power driver. This new accelerator relies on three new components: the ultra-high gradient insulator, the asymmetric BlurnleiU and low jitter switches. In this report, we focused our attention on the first two components of the DWA system the insulators and the asymmetric Bhunlein. First, we sought to develop the necessary design tools to model and scale the behavior of the high gra&ent insulator. To perform this taslq we concentrated on modeling the discharge processes (i.e., initiation and creation of the surface discharge). In additio~because these high gradient structures exhibit favorable microwave properties in certain accelerator configurations, we pefiormed experiments and calculations to determine the relevant electromagnetic properties. Second, we performed circuit modeling to understand energy coupling to dynamic loads by the asymmetric Blumlein. Further, we have experimentally observed a non-linear coupling effect in certain asymmetric Blumlein configurations. That is, as these structures are stacked into a complete module, the output voltage does not sum linearly and a lower than expected output voltage results. Although we solved this effect experimentally, we performed calculations to understand this effect more filly to allow better optimization of this DWA pulse-forming line system. A new accelerator technology, the dielectric wall accelerator (DWA), is potentially an ultra compact accelerator/pulsed power driver [1]. Because of its compact size (which translates into lower cost), it has potential applications in several defase missions and in the commercial sector. It utilizes three principal components to achieve a high gradient in a compact structure. These components include the insulator, the asymmetric Blumlei% and the switches.A primary component that limits the acceleration gradient in the DWA is the vacuum insulator. We have expanded on the initial work [2], and fi.nther studied and developed this component over the past several years [3,4]. For short pulse systems, these structures have withstood 20 MV/m gradients in the presence of a plasma cathode and a 1 kA electron beam.The asymmetric Bhnnlein is a novel method for generating a f~electrical pulse in a single step process (F&ure 1). The system consists of a stacked series of these circular modules and generates a high voltage when switched. Each Blurnlein is composed of two dielectric layers with differing permittivities. On each surface and between the dielectric layers are conductors that form two parallel plate radial transmission lines. The lower permittivity side of the structure is referred to as the slow line. The higher permittivity side of the structure is referred to as the fiist line.Operation of the Blumlein is as follows. The center electrode between the f~and slow line is initially charged to a high potential. Because the two lines have opposite polarities, there is no net voltage across the i...

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Section: B Insulator Scalingmentioning

confidence: 99%

Advanced accelerator theory development

Sampayan¹,

Houck²,

Poole³

et al. 1998

Self Cite

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“…HGIs are tolerant of being placed in direct view of high-current electron [8,9] and ion [10] beams. In addition, they have microwave properties that are useful for accelerators [11]. HGIs are a key enabling technology for a series of new, innovative accelerator concepts, including improved induction cells [12,13], novel optically-triggered high-voltage switches [14], and dielectric-wall accelerators [9,[15][16][17][18].…”

Section: Introductionmentioning

confidence: 99%

Multilayer High-Gradient Insulators

Harris

2006

2006 International Symposium on Discharges and Electrical Insulation in Vacuum

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High voltage systems operated in vacuum require insulating materials to maintain spacing between conductors held at different potentials, and may be used to maintain a nonconductive vacuum boundary. Traditional vacuum insulators generally consist of a single material, but insulating structures composed of alternating layers of dielectric and metal can also be built.These "High-Gradient Insulators" have been experimentally shown to withstand higher voltage gradients than comparable conventional insulators. As a result, they have application to a wide range of highvoltage vacuum systems where compact size is important. This paper describes ongoing research on these structures, as well as the current theoretical understanding driving this work.

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“…In recent impedance experiments [7] it was shown that the impedance value has a strong dependence on dielectric-tometal thickness ratio. Suitability for induction cell application also requires evaluation of the radial length and position of the insulator in the gap and its effect on impedance.…”

Section: High Gradient Insulator Structurementioning

confidence: 99%