Passive levitation of small particles in vacuum: Possible applications to vacuum gauging

Abstract

Articles you may be interested inEffect of a vacuum ion gauge on the contamination of a hydrogenpassivated silicon surface Most techniques for levitating small objects in a vacuum employ fluctuating electric or magnetic fields, often controlled by feedback from a position-sensing device to obtain the desired stability. We describe an alternative technique, diamagnetic levitation, which is particularly useful where compactness and simplicity are important. Diamagnetic levitation is passive in that steady magnetic fields are used and no position sensing or feedback are required. The theoretical background and prior developments are summarized. Two basic configurations, in which the magnetic fields are either vertical or horizontal, are distinguished. Particles of graphite and bismuth in sizes down to the micron range have been levitated in experimental systems of these types. Observations of particle motion as a result of interactions with the surrounding gas molecules are discussed. Many of the observed effects are pressure dependent. Several types of vacuum gauges based on these principles are suggested.

Magnetic Levitation in Chemistry, Materials Science, and Biochemistry

“…From the Contents MagLev is at echnique that suspends objects against the force of gravity using magnetic interactions,a nd separates them by density using ac ompetition between gravitational and magnetic fields and field gradients.Historically,the term "magnetic levitation" has been used most commonly in two distinct areas of applications:(i) suspension and propulsion of vehicles,b earings,a nd flywheels with magnets, [26,27] and (ii)suspension of diamagnetic matter (including the exceptionally diamagnetic materials,g raphite and bismuth [28] )i n the magnetic field of ap aramagnetic fluid or gas (especially liquid O 2 ), or in vacuum. This Review addresses only the latter type of magnetic levitation, in which the suspended object experiences aforce-reflecting the relative magnitude of the interaction of the object and the suspending medium with the applied magnetic field-that is sufficiently large to overcome the effect of gravity,and thus,tolevitate the object in the suspending medium.…”

Recent Advances in Magnetic Levitation: A Biological Approach from Diagnostics to Tissue Engineering

“…The magnetic levitation concept was introduced in the 1960s, where a friction-free suspension was enabled for graphite disk under vacuum by utilizing diamagnetic levitation methodology . Afterward, the magnetic levitation system was developed for density-based mineral , and metal separation . Later, the levitation system was improved for density measurements of solid and organic liquids .…”

“…32 Afterward, the magnetic levitation system was developed for density-based mineral 33,34 and metal separation. 35 Later, the levitation system was improved for density measurements of solid and organic liquids. 36 A very well-known example of the magnetic levitation is the levitating frog, where the whole complex organism levitated in the air environment.…”

Magnetic Levitation Based Applications in Bioscience

“…In this study, the diamagnetically levitated ultramicromanometer was described where frictionfree suspension was produced via magnetic induction for graphite disk to measure absolute pressure down to 10 À10 Torr [15]. Later, density-based separation was carried out for minerals [16] and metals [17] by magnetic levitation principle. In another study, improvement of magnetic levitation system has been studied to measure the density differences of liquids and solids [18][19][20].…”