Abstract: A ferrite layer formation process that may be performed at a lower temperature than conventional ferrite formation processes. The formation process may produce highly anisotropic structures. A ferrite layer is deposited on a substrate while the substrate is exposed to a magnetic field. An intermediate layer may be positioned between the substrate and the ferrite to promote bonding of the ferrite to the substrate. The process may be performed at temperatures less than 300° C. Ferrite film anisotropy may be achieved by embodiments of the invention in the range of about 1000 dyn-cm/cm3 to about 2×106 dyn-cm/cm3.

Abstract: An attenuating embedded phase shift photomask blank that produces a phase shift of the transmitted light is formed with an optically translucent film made of metal, silicon, nitrogen or metal, silicon, nitrogen and oxygen. A wide range of optical transmission (0.001% up to 20% at 193 nm) is obtained by this process. A post deposition process is implemented to obtain the desired properties (stability of optical properties with respect to laser irradiation and acid treatment) for use in industry. A special fabrication process for the sputter target is implemented to lower the defects of the film.

Abstract: Non-spherical particles including a major dimension, for example flakes of material, are positioned with the major dimension oriented generally along an article surface in respect to which the particle is disposed. The particles, disposed in a fluid medium, the viscosity of which can be increased to secure the particles in position, are positioned using a force on the particles. The force includes torque force from a magnetic field, force from flow of the fluid medium, the force of gravity, and the force of surface tension alone or in combination with the force of gravity.

Abstract: The magnetic and magnetotransport properties of field-aligned single domain half-metallic CrO2 powders have been studied. Needle-shaped nanoparticles of CrO2 have been aligned in a strong magnetic field. The aligned powder sample shows a strong anisotropy along the alignment direction. The conduction mechanism of the aligned CrO2 powder sample has been examined and is consistent with the intergranular spin dependent tunneling. Negative tunneling magnetoresistance (TMR) of about 41% is achieved in a small field in the vicinity of the coercive field at 5 K. The magnetoresistance (MR) versus field curve shows two well-separated narrow peaks at the coercive fields and resembles that of a magnetic tunnel junction. This junction-like MR results from the narrow switching field distribution of the aligned powders. The results suggest that the aligned magnetic CrO2 particles may find novel applications in spin transport structures and devices.

Abstract: Construction substrates that have one or more coatings are disclosed. In one embodiment the coating is an adhesive mixture that is magnetically induced to attract a magnetic template. The template that is magnetic or magnetically attracted, that is applied to a construction substrate, is used to create a pattern when a subsequent coating is applied to the substrate. It is emphasized that this abstract is provided to comply with the rules requiring an abstract that will allow a searcher or other reader to quickly ascertain the subject matter of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope of meaning of the claims.

Abstract: A micromachined magnetometer is built from a rotatable micromachined structure on which is deposited a ferromagnetic material magnetized along an axis parallel to the substrate. A structure rotatable about the Z-axis can be used to detect external magnetic fields along the X-axis or the Y-axis, depending on the orientation of the magnetic moment of the ferromagnetic material. A structure rotatable about the X-axis or the Y-axis can be used to detect external magnetic fields along the Z-axis. By combining two or three of these structures, a dual-axis or three-axis magnetometer is obtained.

Abstract: A method and apparatus for manufacturing optical components. A burner generates soot, and a surface area collector collects the soot. The burner is disposed such that the soot collected within the surface area collector is substantially not reheated by subsequently deposited soot. Magnetic forces direct the soot to desired location(s) within the surface area collector. The surface area collector operates at relatively low temperatures sufficient to retain rather volatile substances, such as fluorine, in the soot.

Abstract: A method for forming segmented through holes in a printed circuit board. The segmented through holes comprise a plurality of electrically conductive pathways disposed on the walls of a single through hole. The segmented through hole can be disposed in a two sided circuit board assembly or in a composite, multi layer circuit board assembly.

Abstract: The present invention includes coating composition having magnetic properties for application to a substrate. The coating composition includes a plurality of strontium and or barium hexaferrite particles having a random magnetic pole alignment. The coating composition also includes a binder adhesive capable of suspending the strontium hexaferrite particles. The binder adhesive is a natural rubber capable of adhering in a substantially thin film to the substrate. The strontium hexaferrite particles are normally present between 50% to 98% of the coating composition's total weight when dried on the substrate. The thickness of the film of the coating composition ranges from 0.5 mils to 20 mils, and has 6 to 24 magnetic pole changes per linear inch. The binder adhesive allows for manipulation of the strontium hexaferrite particles to a non-random magnetic pole alignment after the ferromagnetic particles have dried in the binder adhesive on the substrate.

Abstract: A circuit pattern is formed with an electrically conductive paste composed by mixing electrically conductive fillers, the shapes of which have aspect ratios, and a magnetic material, a shape of which has an aspect ratio, in a resin 4. In addition, a circuit pattern is formed with complexes 10 of electrically conductive fillers, the shapes of which have aspect ratios, and a magnetic material 2, and the circuit pattern 21 is hardened while a magnetic line of force is applied in the thickness direction of the circuit pattern 21.

Abstract: A method for modifying a porous mechanical component by using an ER or MR substance including the steps of providing at least one porous component having a porosity sufficient to receive the MR substance within a plurality of pores and impregnating the component with the MR substance.

Abstract: A method for fabricating a magneto-optic modulator, such as for use with a solid state ring resonator gyroscope. The method includes inducing a magnetic field at a substrate holder as a layer of magnetic material is being deposited on a substrate. The magnetic field helps to optimally orient the deposited magnetic material layer to improve the characteristics of the magneto-optic modulator. In addition to inducing a magnetic field, a low energy ion beam may be applied to optimize orientation. The method can be used to fabricate a magneto-optic modulator on a substrate containing a partially fabricated ring resonator without destroying previously fabricated components.

Abstract: A substrate processing method and a substrate processing apparatus are provided to remove a processing liquid from a substrate without using an organic solvent. Upon completion of liquid treatment to dip the substrate W in the processing liquid 30, when exposing a substrate W out of a processing liquid 30 for its removal, the liquid 30 is subjected to an electric field to generate an electric current on the liquid surface and also a magnetic field B. With the arrangement of the electric field and the magnetic field, an electromagnetic force F is produced and applied on the liquid 30 in a direction to leave from a surface of the substrate W.

Abstract: Magnetic field sensors and magnetic memories have at least two magnetoresistive bridge elements (A,B,C,D), wherein each magnetoresistive element comprises a free (F) and a pinned (P) ferromagnetic layer. The magnetization directions of pinned ferromagnetic layers are different for the two bridge elements. In the method, in a first deposition step, a first ferromagnetic layer of one of the two said elements is deposited, during which deposition a magnetic field is applied to pin the magnetization direction MP in the first ferromagnetic layer in a first direction. Then, in a second deposition step, a second ferromagnetic layer of the other of the two said elements is deposited, during which deposition a magnetic field is applied to pin the magnetization direction in the second ferromagnetic layer in a second direction different from, preferably opposite to, the magnetization direction in the first ferromagnetic layer.

Abstract: The present invention relates to a device and method for dusting smooth or sheet-like products, comprising at least one duster for spraying an air/powder mixture on said products. In order to ensure efficient dusting with no dirt accumulation in the printer or the surrounding area, it is suggested that part of the powder particles be magnetized and means be provided for creating a magnetic field in the powder deposit area so that said powder particles are subjected to a force drawing them towards the product.

Abstract: A method for impregnating a porous surface with a magneto-rheological substance includes the steps of providing a porous surface with a porosity sufficient to receive the magneto-rheological substance within the pores and covering a portion of one side of the porous surface with the magneto-rheological substance. The method further includes the step of providing a magnet on the opposite side of the porous surface to apply a magnetic field and draw the magneto-rheological substance into the porous surface.

Abstract: This invention relates to a method of using a laser to produce a decorative appearance on the surface of a bumper. More specifically, the present invention relates to a laser alloying method to create a decorative alloyed layer on the surface of a bumper.

Abstract: One aspect of the present invention provides a method of producing a security document, including the steps of: (a) forming a sheet-like substrate of plastics material having first and second opposing surfaces, (b) coating a first layer of polymer material containing magnetic particles on the first opposing surface, (c) melting at least a portion of the first layer such that the magnetic particles can orient under the influence of a magnetic field, (d) applying the magnetic field so as to form a magnetic watermark, and (e) allowing the first layer portion to cool so as to fix the orientation of the magnetic particles

Abstract: A method of inducing biaxial particle alignment in a body of crystalline particles of a material such as a high temperature superconducting material, having anisotropic magnetic susceptibility so that at least a major portion of the crystalline particles have at least two crystalline axes generally parallel, comprises subjecting the particles to a magnetic field which varies cyclically relative to the body of crystalline particles with time, and which has an average magnitude which is a maximum in a first direction, a lower average magnitude in a second direction generally orthogonal to said first direction and a minimum or zero average magnitude in a third direction generally orthogonal to said first and second directions. Alignment of the axis of maximum magnetic susceptibility of the particles generally with the direction of maximum average magnitude and the axis of minimum magnetic susceptibility of the particles generally with the minimum or zero average magnitude direction is induced.

Abstract: A non-magnetic substance particle arrangement method is provided which can regularly arrange non-magnetic substance particles such as abrasive particles very easily and very cost effectively and can be applied to techniques such as micro grinding work, micro component assembly, and micro decorating work. The method includes the steps of: coating a magnetic fluid mixed with the non-magnetic substance particles on a surface of a magnetic recording medium recorded with a magnetic pattern; and applying a uniform d.c. magnetic field or an a.c. magnetic field superposed upon the d.c. magnetic field to the surface of the magnetic recording medium to form the non-magnetic substances in an in-plane of the magnetic recording medium or cubically on the magnetic recording medium.

Abstract: Process for the at least partial direct coating of an extensible backing material with a pressure-sensitive adhesive composition, the backing material being guided by a transporting apparatus against a coating apparatus in such a way that the coating apparatus applies the pressure-sensitive adhesive composition to the backing material, characterized in that the coating apparatus is abhesively treated.

Abstract: This invention permits formation of a magnetic coating excelling in the degree of orientation in spite of a decrease in the thickness thereof and ensures impartation of a high degree of packing and high durability to the magnetic layer of a small thickness because of the infallible presence of a backcoat layer in an undried state (particularly a wet state) while the magnetic layer is in an undried state (particularly a wet state). It also allows efficient formation of a backcoat layer which used to impose a heavy load on the conventional process of manufacture. Preferably, this invention has the calendering work performed in the in-line system such that the surface quality of the magnetic layer may be exalted by improving the operational efficiency of the calendering step and, as a result, the loss of the applied layer of the paint which used to occur during the course of the calendering step in the conventional separate line may be decreased.

Abstract: An inductive write head includes a first pole and a second pole that form a yoke having a write gap between the first pole and second pole. The second pole is formed of a particular Co100-a-bZRaCRb compound. More specifically, the second pole is formed where “a” is in the range of about 2 atomic percent to about 18 atomic percent, and “b” is in the range of about 0.5 atomic percent to about 6 atomic percent. The magnetic write element also includes a conductive coil which lies between the first pole and the second pole. The inductive write head also includes a first yoke pedestal attached to the first pole, and a second yoke pedestal attached to the second pole, with the write gap formed therebetween. Further, the first yoke pedestal has a pedestal width that defines the write element trackwidth and that is smaller than the pedestal width of the second yoke pedestal.

Abstract: A molded magnetic article and fabrication method are provided. Particles of ferromagnetic material embedded in a polymer binder are molded under heat and pressure into a geometric shape. Each particle is an oblate spheroid having a radius-to-thickness aspect ratio approximately in the range of 15-30. Each oblate spheroid has flattened poles that are substantially in perpendicular alignment to a direction of the molding pressure throughout the geometric shape.

Abstract: A method for forming an etch mask is described. In particular, an etch mask is formed using masking particles positionally restrained by a matrix medium. Either the masking particles or the matrix medium is more magnetically conductive with respect to the other. A magnetic field is applied for making a random distribution of the masking particles less random. Consequently, agglomeration of the masking particles is reduced. Masking particles with submicron dimensions may be used for providing features of less than a micron. The mask formed may be an etch mask employed in forming a field emitter tip for a field emission display.

Abstract: A composite magnetic material showing reduced losses and reduced permeability when it is subjected to a magnetic field at frequencies below approximately 100 MHz. It comprises magnetic particles in the form of wafers dispersed in a dielectric binder. The polycrystalline magnetic ceramic wafers are oriented so that their main faces are substantially parallel to the magnetic field.Application especially to cores of inductors or transformers.

Abstract: A method for creating a magnetically permeable film on a substrate surface by deposition of successive layers of a magnetic material, during deposition of each layer a magnetic field being provided near said surface having a field direction substantially parallel to the surface. In order to tune the permeability of the magnetic material the method builds up the magnetically permeable film by forming each layer by depositing a ferromagnetic material to a thickness maximally corresponding to substantially ##EQU1## where L.sub.ex is equal to ##EQU2## with A being the exchange constant of the ferromagnetic material and K.sub.u being the uniaxial anisotropy constant, and changing the magnetic field direction during formation of said layer by an angle other than substantially 180.degree..

Abstract: Smooth, patterned substrates useful in producing decorative cookware are formed by coating a base with a mixture of fluoropolymer and magnetic flakes and magnetically inducing an image in the polymer coating composition. The baked fluoropolymer release coating contains magnetizable flakes, a portion of the flakes being oriented in the plane of the substrate and a portion of said flakes being magnetically reoriented to form a pattern in the coating which is observed in reflected light, the flakes having a longest dimension which is greater than the thickness of said coating. The patterned substrate is formed by applying magnetic force through the edges of a magnetizable die positioned under a coated base to induce an imaging effect or pattern. The coating composition is then cured resulting in a smooth surface, patterned nonstick finish on the substrate.

Abstract: Servo-pattern information is magnetically recorded on a product disc by magnetic print-through from a master medium. The master servo-writing medium is brought into close proximity with the product "slave" disc, and the two are subjected to an external magnetic field which assists in transferring magnetic servo-patterns to the slave disc in a print-through process. The preferred external magnetic field alternates and rotates with respect to the master/slave combination. In an alternative product disc structure, the magnetic layer is magnetically altered in a servo-pattern configuration. Non-magnetic portions of the servo pattern are created which define both gray code and servo burst information for the product disc.

Abstract: The present invention provides a method of producing a magnetoresistive element in which a laminate including a free ferromagnetic layer in which at least magnetization is freely rotated according to an external magnetic field, a non-magnetic layer, and a pinned ferromagnetic layer in which reversal of magnetization is pinned is formed, and is heat-treated for setting different directions of the easy axis of magnetization of the free ferromagnetic layer and the pinned ferromagnetic layer under different conditions. In the heat treatment, first annealing is performed at the predetermined temperature in a magnetic field applied in a first direction, and second annealing is performed in a magnetic field applied in a second direction substantially perpendicular to the first direction so that the easy axis of magnetization of the free ferromagnetic layer is substantially perpendicular to that of the pinned ferromagnetic layer.

Abstract: Methods and devices for producing plasmas of more uniform density and greater height than plasmas generated by previously known magnetron-type plasma-generating devices. The present invention utilizes electrodes containing multiple magnets positioned such that like magnetic poles of the magnets are all facing in substantially the same direction.

Abstract: A method of fabricating a tag or marker carrying or intended to carry a magnetic code is described. The method comprises applying a particulate magnetic material to a surface region of the tag by a printing or transfer process. The particulate magnetic material is generally deposited in the form of discrete elements or indicia. A tag thus produced can be coded magnetically by magnetising the elements or indicia, e.g. with a permanent magnet. This provides a very versatile and relatively rapid means of generating coded tags or labels virtually without limit on the variety of codes which may be adopted.

Abstract: A vacuum arc evaporation method of disposing a vacuum arc evaporation source and a substrate in a vacuum chamber, and introducing ions generated by arc discharge on the surface of the vacuum arc evaporation source to the substrate by means of magnetic fields, thereby forming a film, wherein the substrate is cleaned before forming the film by generating the arc disc while supplying a gas mixture of a nitrogen gas and an argon gas, a xenon gas, or a gas mixture of nitrogen gas and a xenon gas in the vacuum chamber. A film with improved adhesion and surface roughness can be obtained.

Abstract: The present invention provides a process for adhering a liquid to a particulate substrate. The process comprises the steps of:a) providing an apparatus which can create an oscillating magnetic field within a chamber,b) providing particulate magnetic material within the chamber of said apparatus while said oscillating field is active,c) having in the chamber within the oscillating magnetic field a liquid coating material and a particulate substrate to be coated with said liquid,d) and having said magnetic field form a fluidized bed of at least said particulate magnetic material, said liquid coating material coating the surface of the particulate substrate, ande) optionally continuously collecting the coated particulate substrate.The particulate magnetic material may be added to the chamber before or after the magnetic field has been activated to oscillate.

Abstract: A polarizing plate includes a polarizing layer for controlling a light and producing a polarized light, the polarizing layer having a particle dispersing medium with a property of light transmission and bar-like polarizing particles which are dispersed in the particle dispersing medium and arranged in a constant direction with a magnetic field, where each of the bar-like polarizing particles is provided with a bar-like ferromagnetic particle of chromium dioxide, whose surface is coated with a conductive film.

Abstract: Methods and devices for producing plasmas of more uniform density and greater height than plasmas generated by previously known magnetron-type plasma-generating devices. The present invention utilizes electrodes containing multiple magnets positioned such that like magnetic poles of the magnets are all facing in substantially the same direction.

Abstract: A protective mask is formed of an annular magnetic sheet. Such a sheet may be used to cover annular surfaces to be protected. Adhesive is formed on one side of the sheet. In use, a fluid impervious sheet is adhered to the first side and across the central opening of the annular magnetic sheet. A method of protecting a metallic workpiece during treatment, the metallic workpiece having a portion to be protected during treatment, for example a raised face of a flanged pipe, the method comprising the steps of magnetically attaching a protective mask to the portion of the metallic workpiece to be protected, the protective mask being formed of an annular magnetic sheet and treating the workpiece, such as by painting or sandblasting. A method of protecting a pipe during transportation of the pipe, the pipe having a flanged pipe end and a pipe bore, the method comprising the steps of magnetically attaching a circular protective sheet to the flanged pipe end over the pipe bore; and transporting the pipe.

Abstract: Magnetic composites exhibit distinct flux properties due to gradient interfaces. The composites can be used to improve fuel cells and batteries and effect transport and separation of different chemical species. Devices utilizing the composites include an electrode and improved fuel cells, batteries. Some composites, disposed on the surface of electrodes, prevent passivation of those electrodes and enable direct reformation of liquid fuels. Methods involving these composites provide distinct ways for these composites to be utilized.

Abstract: The invention provides systems and methods for the deposition of an improved diamond-like carbon material, particularly for the production of magnetic recording media. The diamond-like carbon material of the present invention is highly tetrahedral, that is, it features a large number of the sp.sup.3 carbon--carbon bonds which are found within a diamond crystal lattice. The material is also amorphous, providing a combination of short-range order with long-range disorder, and can be deposited as films which are ultrasmooth and continuous at thicknesses substantially lower than known amorphous carbon coating materials. The carbon protective coatings of the present invention will often be hydrogenated. In a preferred method for depositing of these materials, capacitive coupling forms a highly uniform, selectively energized stream of ions from a dense, inductively ionized plasma.

Abstract: The present invention relies upon a free space magnetic field in a pulsed laser deposition (PLD) chamber for forming high quality thin films made from diverted ions from a plume evaporated from an ablated target illuminated by a pulsed laser beam. The magnetic field exerts a qv.times.B Lorentz force upon the ions that is orthogonal to the magnetic field and to their direction of travel in the plume, and curves the ions toward the substrate, while neutral particulates continue to pass by the substrate so that the large neutral particulates are not deposited on the substrate. A shield prevents the deposition of plume species in direct line of sight between the target and the substrate so that only charged ions curved by the magnet are deposited on the substrate. A permanent magnet is used to separate charged species from neutral species.

Abstract: The substrate (30) is placed in an enclosure (34) and is heated by direct electromagnetic coupling with an induction winding (38) to enable a temperature gradient to be established within the substrate, so that the substrate has a higher temperature in its portions remote from its exposed surfaces than in the vicinity of its exposed surfaces. A reaction gas constituting a precursor for the material to be infiltrated is admitted into the enclosure, with the formation of the material being favored in those portions of the substrate that are at higher temperature. According to the invention, the substrate is constituted by a fibrous fabric for which the ratio .rho..sub.r /.rho..sub.c of transversal electrical resistivity over longitudinal electrical resistivity is not less than 1.3, and the ratio .lambda..sub.r /.lambda..sub.c of transversal thermal conductivity over longitudinal conductivity is not less than 0.

Abstract: A method for coating a surface with a magnetic composite material exhibiting distinct flux properties due to gradient interfaces within the composite. Surfaces coated with such a composite can be used to improve fuel cells and to effect improved transport and separation of different species of materials. A wide variety of devices can incorporate such composite-coated surfaces, including separators, fuel cells, electrochemical cells, and electrodes for channeling flux of, or for effecting electrolysis of, magnetic species.

Abstract: A system for coating a substrate with ultra-thin layers in stripes includes moving the substrate through a coating station and forming a composite layer including coating fluids and a carrier fluid. The composite layer flows at a rate that is sufficiently high to form a continuous flowing fluid bridge of composite layer to the substrate surface and to contact the substrate with the flowing composite layer to interpose the coating layers between the substrate and the carrier fluid. The carrier fluid is removed while leaving the coating fluid deposited on the substrate as a coating layer.

Abstract: Methods for providing a low permeability coating on the interior of a refillable plastic container, such as a PET beverage bottle, include coating of a liquid crystal polymer (LCP) by depositing LCP monomers on the interior surface of the container and bi-axially orienting the monomers continuously while reacting the monomers to produce the polymer. The interior surface of the container may be pre-treated to produce free radicals which enhance the attachment of the monomers to the surface. Also, the surface may be post-treated to eliminate unsaturated radicals or free monomers. The application of the monomers to the interior surface of the container can be effected by condensing a gas blend of monomers, by spraying liquid monomers or by filling with liquid monomers and then emptying to leave a residual coating. The monomers are reacted by preheating them or by subjecting them to a heated inert gas.

Abstract: A method for transferring ink on a plate onto a material to be printed by a printing method involves the steps of: providing the ink at predetermined positions on the plate, the ink being sensitive to a field to increase its viscosity so as to have a solidified state or a semi-solidified state; applying the field to the ink to maintain configuration of the ink provided at the predetermined positions on the plate; and transferring the ink onto the material to be printed while maintaining the ink in the solidified or semi-solidified state.

Abstract: Method and apparatus for treating a workpiece implantation surface by causing ions to impact the workpiece implantation surface. An implantation chamber defines a chamber interior into which one or more workpieces can be inserted. A support positions one or more workpieces within an interior region of the implantation chamber so that implantation surfaces of the workpieces are facing the interior region. A dopant material in the form of a gas is injected into the implantation chamber to cause the gas to occupy a region of the implantation chamber in close proximity to the one or more workpieces. A plasma of implantation material is created within the interior region of the implantation chamber. First and second conductive electrodes positioned within the implantation chamber include conductive surfaces in proximity to the chamber interior occupied by the one or more workpieces. A voltage source outside the chamber relatively biases the first and second conductive electrodes.

Abstract: A magnetic material of at least two component parts arranged to have respective structures which mutually are not homogenous, the structure of one part cooperating with the structure of the other to assist the magnetostrictive behaviour of the material. The cooperation can be the structure of one part altering the atomic spacing of the other part. The alteration can be an increase from the usual atomic spacing. There can be contiguous component parts and the cooperation can be a pseudo free surface on at least one part or a reduced restriction of the local moment otherwise achieved by the contiguous component parts. A component can be at least partly an alloy and the alloy can have a ratio other than the usual one for the alloy. One of the components can be non-magnetic.

Abstract: A method for forming a film by a plasma CVD process in which a high density plasma is generated in the presence of a magnetic field is described, characterized by that the electric power for generating the plasma has a pulsed waveform. The electric power typically is supplied by microwave, and the pulsed wave may be a complex wave having a two-step peak, or may be a complex wave obtained by complexing a pulsed wave with a stationary continuous wave of an electromagnetic wave having the same or different wavelength as that of the pulsed wave. The process enables deposition of a uniform film having an excellent adhesion to the substrate, at a reduced power consumption.

Abstract: An optical fiber is releasably held in coil or skein form by a magnetized in film coating on the fiber. Adjacent convolutions are held together by a magnetic field to prevent unintended unravelling of the coil, but the fiber can be rapidly played out at high speed without rupture and with a constant release tension force. The magnetic field has a radial and axial component relative to the coil cylinder. A magnetizing apparatus is disclosed for magnetizing the film. A sensor feedback loop can dynamically adjust the reel-out drag force to dampen vibration modes during reel out which can cause tangle.

Abstract: A randomly varying modulated current is generated and used to drive a magnetic write head in an apparatus for enhancing a randomly varying magnetic security characteristic of a medium. The write head can be positioned adjacent a fluid magnetic slurry for the purpose of altering the location of the various magnetic particles therein in a random fashion. The slurry can then be hardened thermally or using ultraviolet dryers. A circuit which can generate the randomly variable current for the read head includes a modulator which receives a first randomly variable signal and a second, different randomly varying signal which modulates the first signal.