Search

Magnetic printing is quite similar to electrostatic printing. The basic steps consist of recording a magnetic latent image, development of the recording with a magnetic ink and finally transferring the ink to a sheet of paper. Since papers on magnetic printing were first published in 1951, each step of this process has become highly developed. Impactless magnetic printers have been displayed at several conferences during the past few years. This review of the work on magnetic printers shows that printing speeds and print quality equal to electrostatic and ink jet printers can be achieved.

The present paper is devoted to a study of TE surface modes along a ferrite‐dielectric interface, the ferrite magnetization being parallel to the interface. For a transverse propagation with respect to magnetization, two TE‐modes can be found. These unidirectional modes are respectively forward and reverse. The “magnetostatic mode” includes the Damon‐Eshbach mode. The “dynamic mode”, which presents a very wide bandwidth, includes the mode recently described by Hines. Our investigation, carried out on a schematic configuration, gives simple results, which clearly point out the physical behaviour of these very interesting modes.

Strip domains resulting from hard bubbles in a reduced bias field demonstrate a variety of shapes and complex rotational behavior. This paper describes some observations on dumbbell‐shaped, S‐shaped, and C‐shaped domains when excited by time dependent bias‐aiding and bias‐opposing fields.

Motion of magnetic domain walls in magnetic bubble domain materials is discussed in this paper. A steady‐state solution for wall velocity in a magnetic material with orthorhombic anisotropy is used to obtain the conventional expression for the domain wall mobility. After reviewing the experimental situation, it is concluded that the mobility depends in a predictable way on wall width but that its detailed behavior otherwise is not well understood. Limiting wall velocities, nonlinear velocity‐field behavior, and wall inertial effects are considered, and important consequences of the orthorhombic anisotropy appear here; supporting experimental results for these effects are reviewed. Wall motion damping due to anisotropic energy levels in several of the magnetic rare earths is shown to be a limiting factor in obtaining high mobility materials. Other factors which have been shown to be significant, such as surface smoothness, thermal annealing, and irradiation with X‐rays, are also discussed. Finally, express...

This paper describes the conceptual design of a highly reliable 108‐Bit Bubble Domain Memory for the Space Program. The Memory has random access to blocks of closed‐loop shift registers, and utilizes self‐contained bubble domain chips with on‐chip decoding. Tradeoff studies show that the highest reliability and lowest power dissipation is obtained when the memory is organized on a bit‐per‐chip basis. The final design, has 800 bits/register, 128 registers/chip, 16 chips/plane, and 112 planes, of which only seven are activated at a time. A word has 64 data bits +32 checkbits, used in a “16‐adjacent” code to provide correction of any combination of errors in one plane. 100 KHz maximum rotational frequency keeps power low (≤ 25 watts) and also allows asynchronous operation. Data rate is 6.4 megabits/sec, access time is 200 μsec to an 800‐word block and an additional 4 msec (average) to a word.

The storage of information in present day computer systems is shared between high‐speed, high‐cost memories and low‐speed, low‐cost mechanical storage devices. With the advent of cheap bulk memory technology one can envision a storage hierarchy with three levels of storage: buffer, memory, and a mechanical backing store. The individual cost and performance characteristics of the three technologies involved affect the overall computer system cost‐performance. In fact, it is the judicious selection of technologies and system configurations which leads to a well designed storage system. This paper first describes the automatic management of information in a three level storage system where the objective is to keep current information in the fastest device and the rest of the information in the slower devices. Then the evaluation of the storage systems is described for a multiprogramming environment where total system dollars per instruction executed is the criterion for system cost‐performance. Finally, two ...

This paper describes the fabrication and operation of a 52‐bit bubble domain memory chip designed to test the concept of on‐chip magnetic decoding. Access to one of the chip's four shift registers for the read, write, and clear functions is by means of bubble domain decoders utilizing the interaction between a conductor line and a bubble. All other functions are performed by a permalloy overlay driven by an external rotating field. The metallurgy consists of 200 A evaporated permalloy for magnetoresistive sensors. 4000 A electroplated permalloy for propagation etc., and 6000 A electroplated copper for control lines.

This paper describes transport measurements on the magnetic semiconductors Gd3−xvxS4. The vacancies, v, are randomly distributed throughout the lattice and lead to fluctuating repulsive potentials and band tailings. Furthermore, since our largest measured carrier concentrations are small compared to the maximum number of vacancies (∼2.3×1021cm−3), a rigid band model should be applicable. This is in contrast to ordinary semiconductors where the energy dependence of the density of states is generally a strong function of the dopant concentration. Recent transport measurements in Eu doped EuS, which demonstrate the applicability of a model for transport in a band tail of localized states will also be reviewed. The two systems will be compared and discussed in terms of a model first suggested by Cutler and Mott for paramagnetic Ce3−xvxS4, and modified here to include magnetic interactions.

Stabilization of an electrostatic flute‐type instability occurring in a simple magnetic mirror by feedback techniques is discussed. In the first part of the paper a diffuse plasma is considered. The effect of varying the locations of the sensing and suppressing systems is found to alter the stability threshold significantly. In the second part a sharp‐boundary plasma is considered and phase shift and frequency response are included in the feedback terms.

According to the increasing demands for magnetic tape printing especially for video tape, the magnetic tape duplication using a contact process is one of the most attractive solutions. There are two major methods, i. e. anhysteretic transfer and thermal transfer. The coercivity of the master tape should be 2.5 times higher than the slave by computer simulation for anhysteretic transfer, but is not important for thermal transfer. The highest coercivity of the slave tape will be decided by the master tape which, in turn, is limited by the recording head saturation for anhysteretic transfer, however, the thermal characteristics of coercivity and magnetic induction under Tc are more dominant for thermal transfer. The tape surface roughness as well as the coercivity is very important for short wavelength printing. In this paper, the properties of the master and slave tapes for anhysteretic and thermal transfer are discussed with theoretical and experimental results.

The Magneplane1, a large‐gap high speed vehicle concept, has an integrated magnetic suspension‐propulsion system. Two aspects of the system study are discussed in this paper: (a) lift and drag force calculations, and (b) magnet design for the scale model. The first task is to derive general force laws and to develop techniques for analyzing general guideway configurations. Both analytical approaches and computer methods of solution have been investigated. These techniques will be discussed. The second task relates to the verification of the theoretical predictions of system performance using a 1/24 scale model. In order to provide an adequate magnetic field for the 12″ gap, five superconducting coils are required in a full scale vehicle. In the 1/24 scale model permanent magnets are used to give magnetic fields for the 1/2″ gap. Both Alnico and Samarium Cobalt magnets are considered. The design of the magnets made use of the computer program MAGNET2.

The nonspherical or angle dependent part of the intermolecular potential can be studied by a variety of experimental techniques which give direct information about the nonspherical interaction between molecules. In this paper an attempt is made to assess information available on the angle dependent part of the intermolecular potential obtained from acoustical relaxation, NMR, depolarized Rayleigh scattering, flow birefringence, field effects on transport properties of gases and pressure broadening. This information, obtained for simple polyatomic molecules such as N2, CO, H2, HD and CH4, is tabulated as effective cross sections which are matrix elements of a collision operator. The results are discussed from two points of view: the experimentally observed trends which the cross sections tend to follow; the ability of theory to agree and predict such trends and to find relationships between cross sections.