The charged particles storage capacity of microtraps (micro-Penning-Malmberg traps) with large length to radius aspect ratios and radii of the order of tens of microns was explored. Simulation studies of the motions of charged particles were conducted with particle-in-cell WARP code and the Charged Particle Optics (CPO) program. The new design of the trap consisted of an array of microtraps with substantially lower end electrodes potential than conventional Penning-Malmberg traps, which makes this trap quite portable. It was computationally shown that each microtrap with 50 µm radius stored positrons with a density (1.6 × 10 11 cm −3 ) even higher than that in conventional Penning-Malmberg traps (≈ 10 11 cm −3 ) while the confinement voltage was only 10 V . It was presented in this work how to evaluate and lower the numerical noise by controlling the modeling parameters so the simulated plasma can evolve toward computational equilibrium. The local equilibrium distribution, where longitudinal force balance is satisfied along each magnetic field line, was attained in time scales of the simulation for plasmas initialized with a uniform density and Boltzmann energy distribution. The charge clouds developed the expected radial soft edge density distribution and rigid rotation evolved to some extent. To reach global equilibrium (i.e. rigid rotation) is to be reached in longer runs. The plasma confinement time and its thermalization were independent of the length. The length-dependency, reported in experiments, is due to the fabrication and field errors. Computationally, more than one hundred million positrons were trapped in one microtrap with 50 µm radius and 10 cm length immersed in a 7 T uniform, axial magnetic field, and the density scaled as r −2 down to 3 µm. Larger densities were trapped with higher barrier potentials.
The last decade in advanced microelectronics has shown great interest in 3-D architectures, which was paved by multi-wafer alignment technologies. However, many limitations remain in the fabrication of ultratall stacks as the alignment becomes more challenging and very costly. In this paper, a new cost-effective alignment technique was employed using a set of sapphire rods in through-wafer holes. Cross-sectional analysis, edge profilometry, and electron transmission tests showed ∼2 µm alignment tolerances over 1 cm and ∼4 µm over 10-cm tall stacks. An off-angle gold sputtering method was developed to fully coat vias of 5:1 aspect ratio before bonding. Also, a new "Stamping" technique is introduced to coat the vias to a desired height where necessary. In this paper, parallel microtubes with the aspect ratios of 1000:1 were formed by aligning ∼200 wafers, each including 20 000 gold-coated vias for storing charged particles.[2016-0049]
A unique approach for the fabrication of long-aspect ratio microtubes is presented for an antimatter trap. Conventionally, non-neutral antimatter is stored using a Penning-Malmberg trap, a single tube with aspect ratios being of the order of less than 10:1. Parallel microtubes with aspect ratios of 1000:1 have the potential to store many orders of magnitude more. The silicon industry has paved the way to microelectromechanical systems technologies which have been utilised in this research. Standard processes such as photolithography, deep reactive ion etching, sputtering and thermo-compression bonding were all used; however, unique methods of these processes were developed to overcome many engineering challenges and realise successful trapping.
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