Magnetic Bumps Research Articles

On the detection interfaces for inductive type tactile sensors

This study presents the investigation of detection interface for the inductive type tactile sensor consisted of a polymer encapsulated CMOS chip with coils and a magnetic bump. The normal tactile load will change the distance between the magnetic bump and coils, and the tactile load is then detected by the magnetic flux change of the coils. Thus, the detection interfaces include (1) the magnetic bump which acts as the contact interface, and (2) the coils (on the CMOS chip) which act as the signal pick-up interface. For the contact interface, the size and material of the magnetic bump will influence the magnetic flux of the inductive tactile sensor. The signal outputs resulted from the magnetic tactile bumps of different materials and sizes are studied. Moreover, the force responses, hysteresis measurements, and misalignment issues for magnetic bumps of different sizes are also investigated. For signal pick-up interface, two coil designs are presented to offer different sensing approaches for the inductive tactile sensor. Since the CMOS chip is implemented using the commercially available standard process (the TSMC 0.35 μm 2P4M CMOS process), multi-layer coils are achieved by using the four metal films.

Symbolic dynamics of magnetic bumps

For n convex magnetic bumps in the plane, whose boundary has a curvature somewhat smaller than the absolute value of the constant magnetic field inside the bump, we construct a complete symbolic dynamics of a classical particle moving with speed one.

Ion reflection by shock waves and pulse generation by cross-field ion beams

Comparisons are made of two different particle simulations: one for the study of plasma-based accelerators (Gueroult & Fisch, Phys. Plasmas, vol. 23, 2016, 032113) and the other for the study of shock formation in the interstellar medium (Yamauchi & Ohsawa, Phys. Plasmas, vol. 14, 2007, 053110). In the former, shock waves used for plasma density control create ion beams by reflection. In the latter, a fast and dense beam of exploding ions penetrates a surrounding plasma. In both simulations, magnetic bumps are generated from the motion of ion beams perpendicular to a magnetic field. Despite the apparent differences of their purposes, configurations and spatial scales, the two simulations show strong similarities in the generation processes and effects of the bumps, suggesting that these are not rare plasma phenomena. The bump created by the exploding ions develops into backward and forward magnetosonic pulses.

RF Beam Deflection Measurements and Corrections in the SLC Linac

The requirements of RF acceleration in the SLC Linac to produce high energy beams are complicated by the presence of small transverse RF beam deflections which arise from several sources. These RF deflections place stringent tolerances on the phase and amplitude stability of the klystrons. They also force the use of special magnetic bumps to correct the trajectories of oppositely charged beams that will pass down the linac. If left unabated, RF deflections can limit the performance of the SLC. There are several methods to reduce the deflections. Many measurements of RF deflections have been made in the low energy part of the linac where the beams are most sensitive.

Formation of Electrostatic Potential Barrier between Different Plasmas

A potential depression is formed between two magnetized plasmas with different electron temperatures and ion species in the absence of electric current passing through them. The depression is deep enough to reflect both groups of electrons, reducing thermal contact between the plasmas. By addition of a magnetic bump to a uniform magnetic field, the potential dip is localized around the mirror point. A dependence of the phenomenon on neutral-gas pressure is also clarified.

Extraction Studies for the Modified Nevis Synchrocyclotron

Computer studies of a regenerative beam extraction system using magnetic peeler-regenerator have been performed. We have also investigated the use of a time varying first harmonic magnetic bump as a beam stretcher. The results indicate, that we can expect a turn separation of the order of 0.8 in. at the mouth of the magnetic channel. The time varying bump makes it possible to stretch the external beam over most of the RF-off time of the acceleration cycle. For the, magnetic channel, a current configuration has been found which does not perturb the main cyclotron field outside itself and reduces the field by 4 kG inside the channel. The step from no field to full field is only 0.2 in. This 4 kG field extending over a distance of 20-in. is sufficient to lead the beam out of the machine.

Magnetic contractor mechanism in betatrons and synchrotrons

A comparative study of different types of magnetic transients (contractors and magnetic “bumps”), carried out on the 8-MeV betatron of the Institute of Atomic Physics, showed that their mechanism of operation cannot be thought of a simple orbit contraction, but merely as a convenient means of altering the parameters of the collision between the injected beam and the chamber walls. The actual orbit radius contraction was found experimentally much lower that the one necessary for the electrons to miss the injection gun. Moreover, a similarity of effects of contractor-type transient and of sectorial magnetic bump was pointed out, although the former does contract the orbit and the latter does not. These facts fit best with the central shift mechanism (CSM) theory of electron capture. The effect of relative injection and contraction timing was also studied and conclusions were drawn on the higher efficiency of injecting electrons with instantaneous radii near the equilibrium radius, and on the most convenient form of contractor pulse.

Manipulation of the ZGS Beam for Targeting

The feeding of as many as four experimental areas from a single ZGS pulse calls for a flexible system for controlling the spill of the beam. The beam is displaced radially into as many as four targets plunged into position after radial damping of the beam has occurred. Beam spills have been adjusted in time duration from 5 microseconds to 500 milliseconds during a flat-top period of the main magnet cycle. Spills shorter than about 0.5 millisecond are accomplished by a pulsed magnetic bump which displaces the orbit center. Spills longer than about 0.2 milliseconds are accomplished by programmed adjustment of the accelerating rf so as to expand or contract the orbit radius. Radiation level monitors in the vicinity of the targets or in the experimental beam lines are used to feedback a signal into the rf program which results in the reduction of spill irregularities due to main magnet ripple and other noises. Such a spill has rf structure and is on from 25% to 50% of the time. The repeatability for placing the beam into a given position for targeting is about 0.01 inch without employing feedback from radiation level monitors. A description of the equipment and instrumentation is given along with the performance.