Fast Switching Ferroelectric Materials for Accelerator Applications

Abstract

Abstract. Fast switching (< 10 nsec) measurement results on the recently developed BST(M) (barium strontium titanium oxide composition with magnesium-based additions) ferroelectric materials are presented. These materials can be used as the basis for new advanced technology components suitable for high-gradient accelerators. A ferroelectric ceramic has an electric field-dependent dielectric permittivity that can be altered by applying a bias voltage. Ferroelectric materials offer significant benefits for linear collider applications, in particular, for switching and control elements where a very short response time of <10 nsec is required. The measurement results presented here show that the new BST(M) ceramic exhibits a high tunability factor: a bias field of 40-50 kV/cm reduces the permittivity by a factor of 1.3-1.5. The recently developed technology of gold biasing contact deposition on large diameter (110 cm) thin wall ferroelectric rings allowed ~few nsec switching times in witness sample experiments. The ferroelectric rings can be used at high pulsed power (tens of megawatts) for X-band components as well as at high average power in the range of a few kilowatts for the L-band phaseshifter, under development for optimization of the ILC rf coupling. Accelerator applications include fast active X-band and Ka-band high-power ferroelectric switches, high-power X-band and L-band phase shifters, and tunable dielectric-loaded accelerating structures.

Anomalous Correlation between Dielectric Constant and Tunability in (Ba,Sr)TiO3–MgO–Mg2SiO4 Composite Ceramics

“…[1][2][3] Recently, the accelerator applications of BST-based ferroelectrics were also reported: bulk BST ferroelectrics can be used as active elements of electrically controlled switches and phase shifters in pulse compressors or power distribution circuits of future linear colliders as well as tuning layers for the dielectric-based accelerating structures. [4][5][6][7] The main requirement for the electrical properties of ceramic materials for tunable microwave applications is a combination of relatively low dielectric constant, low loss tangents, and high dielectric tunability. 8,9 However, the high inherent material loss and high dielectric constant of pure BST has restricted its application in tunable microwave devices.…”

“…The DC electric field‐dependent dielectric constant can be used to develop the phase shifting elements in phased array antennas and tuning elements in devices operating at microwave frequencies . Recently, the accelerator applications of BST‐based ferroelectrics were also reported: bulk BST ferroelectrics can be used as active elements of electrically controlled switches and phase shifters in pulse compressors or power distribution circuits of future linear colliders as well as tuning layers for the dielectric‐based accelerating structures . The main requirement for the electrical properties of ceramic materials for tunable microwave applications is a combination of relatively low dielectric constant, low loss tangents, and high dielectric tunability .…”

Ferroelectric-Dielectric Solid Solution and Composites for Tunable Microwave Application

“…Depending on the shape of the linear dielectrics and on the dielectric constants of the components, the impact of each of these two effects on the composite tunability is different and the second effect may be stronger (Sherman et al 2006 The multiple-phase ferroelectric-dielectric composites are useful for tunable microwave applications requiring low dielectric constant and make the impedance match more easily. The ferroelectric-dielectric composite bulk ceramics show promising application, especially in accelerator, as active elements of electrically controlled switches and phase shifters in pulse compressors or power distribution circuits of future linear colliders as well as tuning layers for the dielectric based accelerating structures (Kanareykin et al 2006(Kanareykin et al , 2009a(Kanareykin et al , 2009b. The ferroelectric bulk ceramics can also be used in ferroelectric lens (Rao et al 1999).…”

Tuneability amplification factor and loss of high-contrast composites

“…When we dilute ferroelectric with dielectric inclusions, the local energy " 0 ðx, 0ÞjrNðxÞj 2 (which determines the loss) is ''forced out'' from dielectric inclusions into ferroelectric matrix and the effective loss is determined, in fact, by the loss property of the matrix. There has been reported [26] a high-contrast ferroelectric-dielectric composite material with low loss characteristics. This experimental data cannot be explained in the framework of composite materials theory, and the reported decreasing of effective loss is, evidently, a phenomenon not of composite nature.…”