We study the focusing of large neutral molecules in a molecular beam using electric fields. Since all quantum states of these molecules are high-field seeking under the practical experimental conditions, alternating gradient (AG) focusing has to be applied. The optimal ac frequency that yields the highest transmission depends on m/μ, where μ is the dipole moment and m denotes the mass. Therefor...

The preservation of beam quality in a plasma wakefield accelerator driven by ultrahigh intensity and ultralow emittance beams, characteristic of future particle colliders, is a challenge. The electric field of these beams leads to plasma ions motion, resulting in a nonlinear focusing force and emittance growth of the beam. We propose to use an adiabatic matching section consisting of a short pl...

We studied focusing in a two-dimensional metamaterial that was based on a labyrinth structure. We theoretically showed that the labyrinth-based metamaterial exhibits negative indices of refraction between 6 and 6.4 GHz. We experimentally studied the focusing effect by measuring electric field intensities on the output side of the metamaterial when the source was placed in front of the input sid...

We present a technique for simultaneous focusing and energy selection of high-current, mega-electron volt proton beams with the use of radial, transient electric fields (10(7) to 10(10) volts per meter) triggered on the inner walls of a hollow microcylinder by an intense subpicosecond laser pulse. Because of the transient nature of the focusing fields, the proposed method allows selection of a ...

We describe a numerical model initially aimed at simulating the propagation of acoustic surface waves in multilayered structures and show how it can be used to the prediction of the electric response of a non-focusing ultrasonic transducer. We also apply this model to non-destructive evaluation of the elastic properties of porous silicon.

Title of Thesis: LONGITUDINAL EFFECTS AND FOCUSING IN SPACE-CHARGE DOMINATED BEAMS Degree candidate: John Richardson Harris Degree and year: Master of Science, 2002 Thesis directed by: Professor Patrick G. O'Shea Department of Electrical and Computer Engineering The purpose of this thesis is to investigate longitudinal effects in space-charge dominated beams, and to begin design of a longitudin...

This paper reports an analytical method to show the effect of electrostatic and Casimir forces on the pull-in instability and vibration of single nano-plate (SNP) carrying a moving nanoparticle. Governing equations for nonlocal forced vibration of the SNP under a moving nanoparticle considering electrostatic and Casimir forces are derived by using Hamilton’s principle for the case when two ends...

The focusing of electric current by a single p-n junction in graphene is predicted. We show that precise focusing can be achieved by fine-tuning the densities of carriers on the nand p-sides of the junction to equal values, whereas the current distribution in junctions with different densities resembles caustics in optics. This finding can be utilized in the engineering of electronic lenses and...

We study the focusing of a Gaussian laser beam in a microscopic planar cavity when the laser wavelength is resonant in the cavity but the beam divergence is larger than the acceptance angle of the cavity. Using the luminescence of implanted praseodymium ions as a microscopic probe for the total electric field inside the spacer of the microresonator, we investigate theoretically and experimental...

We report on the design and characterization of focusing-curved subwavelength grating couplers for ultra-broadband silicon photonics optical interfaces. With implementation of waveguide dispersion engineered subwavelength structures, an ultra-wide 1-dB bandwidth of over 100 nm (largest reported to date) near 1550 nm is experimentally achieved for transverse-electric polarized light. By tapering...