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Magnetic-Particle-Based Microfluidics
Published in Sushanta K. Mitra, Suman Chakraborty, Fabrication, Implementation, and Applications, 2016
Ranjan Ganguly, Ashok Sinha, Ishwar K. Puri
Microfluidic implementation of IMS has attracted immense interest in the recent past, leading to a large variety of applications. Immunomagnetic separation is achieved via different modes (see Figure 15.18), for example, magnetic trap, flow diverter, or split flow thin (SPLITT) fractionation. In the magnetic trap design, a homogeneous suspension of the target analyte (bound to the magnetic bead) enters the channel across which a transverse magnetic field gradient is imposed. The background fluid may also contain some nontarget entities. The magnetic field gradient and particle-particle interaction lead to capture of the magnetic beads (along with the bound target analyte) within the channel bed (see Figure 15.18a). Several designs are proposed in the literature involving electromagnets with soft magnetic cores, permanent magnets, or a combination of both (Choi et al., 2001; Smistrup et al., 2005a,b; Ramadan et al., 2006)
Erosion of Fuzz Layers Formed in Steady-State Plasma Discharge
Published in Fusion Science and Technology, 2023
V. P. Budaev, S. D. Fedorovich, A. V. Dedov, A. V. Karpov, Yu. V. Martynenko, D. I. Kavyrshin, M. K. Gubkin, M. V. Lukashevsky, A. V. Lazukin, A. V. Zakharenkov, A. P. Sliva, A. Yu. Marchenkov, M. V. Budaeva, Q. V. Tran, K. A. Rogozin, A. A. Konkov, G. B. Vasilyev, D. A. Burmistrov, S. V. Belousov
The PLM-M device, shown in Fig. 1, is a linear plasma trap with an eight-pole multicusp magnetic field configuration. The PLM-M device is an upgraded PLM device (see description of the PLM in Ref. 11) with an upgraded cathode and power supply system. The plasma parameters are similar to the scrape-off layer and divertor plasma in a tokamak. The parameters of the PLM-M device are as follows: cooled discharge vacuum chamber diameter/length of 0.16/0.72 m, magnetic field of 0.02 T on the magnetic trap axis and up to 0.2 T in the cusps, hot plasma column of 3.5 cm in diameter (defined by scraper aperture of the anode), discharge plasma current of more than 35 A, steady-state plasma density up to 5 × 1019 m−3, electron temperature up to 10 eV with a fraction of hot electrons of ~50 eV, and ion plasma flux onto the test sample up to 5 × 1025 m−2s−1. The working gas is helium. Optic spectroscopy, reciprocating Langmuir probes, and pyrometers were used to measure the plasma parameters and thermal plasma load onto the exposed samples in the plasma. The material samples were irradiated with plasma up to 500 min, and thermal plasma heat loads of up to 4 MW/m2 and more were achieved on the surface. The PLM-M is equipped with a laser Nd:YAG LQ529A (λ = 1064 nm, 500 mJ, 10 ns) for laser ablation experiments. The schematic of the experiment with laser ignition is shown in Fig. 1b. The incidence angle of the laser beam on the sample was 20 deg; it leads to an elliptic spot on the sample.
Laser cooling of trapped ions in strongly inhomogeneous magnetic fields
Published in Molecular Physics, 2023
Richard Karl, Yanning Yin, Stefan Willitsch
Doppler laser cooling of a single calcium ion was studied in a hypothetical hybrid trap composed of a linear-quadrupole RF trap and a quadrupolar magnetic trap. For the simulations reported here, we used MHz, and q = −0.08 which correspond to realistic parameters of traps used in our laboratory [54]. The inhomogeneous B-field was assumed to originate from two bar magnets in anti-Helmholtz configuration with dimensions mm as used, e.g. in Ref. [38]. Each magnet was assumed to have a remanence of 1.64 T and the surface-to-surface distance between the two bar magnets was taken as 3.6 mm. A sketch of the assumed setup and a simulation of the B-field are shown in section B in the supplemental material.
Atom chips with free-standing two-dimensional electron gases: advantages and challenges
Published in Journal of Modern Optics, 2018
G. A. Sinuco-León, P. Krüger, T. M. Fromhold
The depth and frequency of the trap are determined by a combination of geometrical factors (e.g. the shape and dimensions of the conductor) and the strength of the magnetic field produced by the current through the chip. For the single-wire magnetic trap, the intensity of the magnetic field is limited by the peak current density, , supported by the conductor. In addition, the power dissipated by the elements in the chip should be small enough to ensure that thermal damage is avoided. This last condition can be satisfied easily when the conductors operate in a regime of large conductivity, which is one of the reasons why metals have so far been the preferred material for magnetic micro-traps.