Conventional Deflection Research Articles

Deflection Routing for Optical Bursts Considering Possibility of Contention at Downstream Nodes

Deflection routing is one of the promising approaches to resolve contention in the optical burst switching networks. In the conventional deflection routing scheme, optical bursts may be unable to traverse the route evaluated to select an outgoing link because of the contention at succeeding downstream transit nodes. As a result, the optical bursts may traverse a different route resulting in a long distance or decreased performance. This paper proposes a deflection routing scheme that considers the possibility of the contention at downstream nodes. This scheme utilizes the expected route distance instead of the static route distance toward a destination node. The expected route distance considers the possibility of contention at each downstream transit node and is calculated using measured link blocking probabilities at each downstream transit node. The selection priority of each outgoing link is given dynamically based on its expected route distance toward a destination node. By considering the possibility of contention at downstream nodes, a routing scheme with high performance can be realized. The loss rate of optical bursts is improved when an imbalanced load is applied to the network, and the loss rate of optical bursts is also improved when the network includes links with extremely different distances.

Performance modeling of an elliptically polarizing undulator under magnetic loading

A 3.9-meter-long elliptically polarizing undulator recently has been designed, constructed, and installed in the storage ring at Synchrotron Radiation Research Center (SRRC) to provide an ultra-brilliant polarizing light source in the soft X-ray range. This undulator is the longest such polarizing device ever constructed, accounting for why its backing beams withstand an enormous magnetic force. Conventional deflection compensation scheme cannot be applied to improve the spectral performance owing to dependence of the magnetic loading on the device's operating modes. This study systematically studies how magnetic loading affects the magnetic field errors of this elliptically polarizing undulator, including numerical calculations and experimental measurements. Ultimately improving the spectral performance of an elliptically polarizing undulator depends on effectively minimizing the deflection sensitivity of the backing beams from the backlash of movable magnetic arrays.

Edgeways electrostatic deflectors with reduced aberrations

Abstract Electrostatic deflection systems in which the deflector plates are edgeways to the beam – i.e. the plates are flat sheets that lie in a plane perpendicular to the beam – are investigated. A deflection system that can deflect in both transverse directions is considered and the geometry is optimized to minimize the aberrations, which are found to be from 4 to 30 times smaller than the aberrations of conventional deflection systems.

Electrostatic deflection aberrations revisited: Solution proposed to an old problem

The deflection of charged particle beams into large angles is more often done with magnetic fields than with electric fields. One reason is that magnetic deflection aberrations are two to three times lower than electrostatic deflection aberrations. Electrostatic deflection aberrations have been re-examined in an attempt to design a 4 k by 5 k pixel cathode ray tube display suitable for digital mammography workstations. Using a novel ray trace program, it has been determined that electrostatic deflection aberrations can be reduced ten-fold by injecting the electron beam at an optimized offset position into a conventional deflection plate assembly. The surprising result is that the “sweet spot” is not near the center where it would be expected based upon looking at the fringe fields. The optimum injection position is offset almost halfway towards the attracting plate. This result has been confirmed in one test configuration. While the mammography application provided the initial motivation to reduce deflection aberrations, the technology may be useful in electron or ion beam lithography, especially so since the design readily accommodates four discrete beams.

Asymmetric far-field patterns emitted by symmetrically pumped twin-stripe lasers in crosscoupled-mode operation

Asymmetric far-field patterns emitted by symmetrically pumped twin-stripe lasers in crosscoupled-mode operation are analysed for the first time. The far field is always deflected to the side with higher carrier density, which is contrary to that of conventional far-field deflection of asymmetrically pumped lasers.

Multiple-beam cathode ray tube design overview

A CRT that simultaneously writes 16 adjacent raster lines is described. The electron beams that write the lines are produced from very small electron guns fabricated on a single sapphire chip using thin-film techniques. Subsequently a single lens is used to focus the 16 beams on the screen, and a conventional magnetic deflection yoke is used to deflect the beams to form the raster. Because the displayed data is handled in parallel, higher content flicker-free images can be displayed. The dynamic corrections required to achieve display contents above 10 Mpixel are discussed.

Proposed Use of the Radio-Frequency Quadrupole Structure to Funnel High-Current Ion Beams

In this paper, we describe a new approach to funneling beams that are initially accelerated in two radio-frequency quadrupole (RFQ) accelerators. Instead of discrete optical elements, we propose to funnel within an RFQ structure, so that during the funneling process the beam is always confined by periodic transverse focusing. Beams with high space charge experience irreversible emittance growth when they emerge from a periodic focusing system. To alleviate this problem, in the proposed funneling system it should be possible to maintain the same focusing periodicity as that of the accelerators preceding the funnel. Also, instead of conventional deflection systems, we propose to use the properties of a modified RFQ structure to deflect two parallel beams toward each other and to merge them into a single final beam. 1 ref., 3 figs.

The Reflected-Beam Kinescope

The reflected-beam kinescope is a short tube particularly suited for picture sizes of 21 inches or more. It retains the conventional gun and external deflection components and is axially symmetric. Although the effective deflection angle is nearly 180°, the deflection power required is equivalent to that used in conventional 90° kinescopes. The electron beam scans through an apertured phosphor screen and is reflected back to the screen by the faceplate. The screen attenuates the beam by a factor of 4, except in the case of a radial scan where a cutout in the center of the screen may be made to permit free passage of the beam. The results of a theoretical and experimental study of the tube are presented. They show the raster to be inherently barrel-distorted. However, the distortion may be corrected in several ways. The resolution is somewhat lower than in standard tubes, although it is considered to be adequate. High detail contrast is obtained.

Oscilloscope tube with travelling wave deflection system and large field of view

The frequency response of conventional deflection systems, i.e. the influence of the transit time, the rise time and oscillations, is discussed in a somewhat abbreviated form. It is shown that an unbalanced or balanced helix system offers great advantages for high-speed oscillography.A new travelling-wave oscilloscope tube is described which possesses a balanced helix system as signal plates. The tube has a very large field of view (1⅜ in. by 4 in.) and an excellent frequency response (90 per cent. sensitivity at approximately 2000 Mc/s) while the sensibility is still in an acceptable range. The question of magnetic vs. electrostatic focusing in a high-speed oscilloscope tube is treated in detail. Typical operating conditions and the performance of the tube are described.

A new approach to kinescope beam convergence

Misconvergence of the beams in color kinescopes because of deflection has been corrected in the past by the use of dynamic convergence devices. Six independent fields are required to deflect three beams without misconvergence. Conventional deflection yokes supply two of these fields; the remaining four are supplied by convergence magnets. This paper describes a more general system that uses six coexistent deflection fields. Such a system is capable of producing deflection without misconvergence, and in contrast to conventional systems produces no loss in color purity tolerance. A particular embodiment of this system is discussed in detail. It employs a six-coil "converger" used in combination with a conventional deflection yoke. The results of an experimental investigation of this embodiment are given.

A new approach to the convergence of multi-beam kinescopes

Misconvergence of the beams in color kinescopes due to deflection has been corrected in the past by the use of dynamic convergence devices. Six independent fields are required to deflect three beams without misconvergence. Conventional deflection yokes supply two of these fields; the remaining four are supplied by convergence magnets. A more general system employs six coexistent deflection fields. Such a system is capable of producing deflection without misconvergence or loss in color purity. This paper discusses the theory and experimental verification of this concept.

Some New Aspects of High-Speed Oscillography

From a consideration of the mechanism of the cathode-ray oscillograph at very high speeds it is shown, in Part I, that conventional deflection systems do not fully realize the possibilities of the cathode-ray tube. By a modification of the shape of the deflector-plates it is theoretically possible, under suitable conditions, to expand the time-scale obtainable with a given time-base generator up to infinity. This gain is obtained at the expense of definition, but brightness is not affected. Relativistic considerations are shown to be irrelevant. The geometry of the deflected electron beam is examined, and an expression derived relating the shape of the effective time-base voltage wave-form, the time-scale, and the shape of the Y-plates. Part II examines some practical factors ignored in the analysis of Part I. These cause various forms of trace distortion, which are classified as (i) intermodulation effects, (ii) mismatching distortion, (iii) transit-time effects, (iv) defocusing and equivalent effects. Possible ways of overcoming a number of these difficulties are described. Some have already been employed with success, but others have not yet been followed up.