Ion Beam Diameter Research Articles

Controllable variable beam diameter ion source based on the Einzel lens

With the development of modern optical systems, high-power laser systems, ultraviolet lithography systems, etc., the requirements for the precision and processing efficiency of optical components continue to increase. Although sub-nanometer precision can be achieved with current ion beam figuring, the introduction of additional removal layers greatly limits its machining efficiency due to the inability of the machine dynamics to satisfy the velocity and acceleration requirements mathematically. Therefore, an efficient figuring technology of controllable variable beam diameter ion beam based on the Einzel lens has been proposed. The simulation results show that the ion beam diameter can be effectively controlled by adjusting the voltage of the Einzel lens. The experimental results show that the ion source can control the ion beam diameter by voltage, and then change the size of the ion beam, and obtain a very small removal function. The FWHM is reduced from 12.1 mm to 10.1 mm, and the peak removal rate is increased by 1.7 times, which significantly improves the removal efficiency and figuring ability. Therefore, this work aims to improve the accuracy of ion beam figuring of high-power laser optical components and address the problem of reduced efficiency caused by additional removal layers in the existing figuring process.

Study the effect of cathode electrode aperture shapes on ion beam properties using SIMION program

Abstract This work was concerned with a simulation study of different cathode electrode aperture shapes (pierce, reversed pierce, cone, reversed cone, triangle, reversed triangle, rectangle, circle, and sphere), which confirms that, pierce and cone shapes are the best extraction apertures. The minimum values of ion beam diameter and ion beam emittance, at collector plate which placed at 30 mm distance from cathode electrode were obtained using pierce and cone shapes. Also, the distance of the ion beam trajectories focal point was studied using different shapes for cathode aperture, which found to be decrease with increasing of the voltage applied to the cathode electrode. The main parameter in this study was the applied voltage to the cathode electrode. It was found that the observed changes on the ion beam parameters in the range 100 - 1500 V, but higher than these values the behavior of diameter, emittance and focal point of the ion beam were quasi-saturated. Also, it was found that the general behavior of ion beam diameter and its emittance nearly the same.

Verification of numerical model of temperature calculations in radio-frequency ion thrusters

A numerical model for temperature calculation in radio-frequency ion thrusters (RIT) is proposed. The equations used for heat fluxes determination differ from those used in the known computational models. A new way of distribution of a radiant power flux caused by the excited atoms and ions of the plasma discharge is proposed. In addition, a new radiant flux caused by recombination of ions and electrons on the surfaces bordering the discharge was taken into consideration. The numerical model was verified based on temperature measurements made with the thruster with an ion beam diameter of 8 cm operating at three different power modes. The temperature measurements were made by thermographic camera focused on blackened areas of the accelerating grid surface.

Formation mechanism and compensation methods of profile error in focused ion beam milling of three-dimensional optical microstructures

The formation mechanism and compensation methods of the profile error in focused ion beam (FIB) bitmap milling of three-dimensional (3D) optical microstructure are studied in this paper. The processing parameters such as ion beam currents, dwell times, and beam overlap ratios on the profile error have an optimized parameters combination of 21 nA, 10 μs, and 50%, and the shape accuracy processed under the conditions is 0.44 μm of P–V and 0.142 μm of RMS, respectively. Inappropriate processing parameters lower either shape accuracy or processing efficiency. By means of an accurate simulation model of the FIB machined 3D profiles, the intrinsic formation mechanism of the profile error can be attributed to ion beam diameters, redeposition effect, and sputter yields, and these factors are inevitable in FIB milling of 3D microstructures. In situ modification and iterative optimization are proposed to compensate the FIB milling error, which both can improve the shape accuracy more than 50%. The in situ modification method needs to load the original bitmap and modified bitmap separately, which is less convenient than the iterative optimization method that only need loading one bitmap file. However, the in situ modification is better than the iterative optimization at decreasing the RMS value of the profile error which indicates the global profiles error of the processed microstructures.

Miniature Ion Source KLAN-10M with a Plasma Neutralizer

The results of testing a new miniature accelerated ion source (KLAN-10M) with a plasma neutralizer are reported. In particular, the operating modes of the source are studied, and the dependences of the ion-beam diameter and the ion current distribution along the output aperture surface on distance are measured. The ion current density with an output-aperture diameter of 7 mm (flat ion optics) is 10.4 mA/cm2, which allows one to precisely correct local errors in the surface shape of the optical components at a low beam divergence (≈15%). The operation of the plasma neutralizer is studied, the resulting electronic current of which provides, for this design, incomplete compensation of the space charge in a beam (the neutralizer current is 10 times less than the current of ions).

Generation of small diameter ion beam for high-precision optical fabrication

Generation of small diameter ion beam for high-precision optical fabrication

Stationary Temperature Distribution in a Rotating Ring-Shaped Target

For a rotating ring-shaped target irradiated by a heavy-ion beam, a differential equation for computing the stationary distribution of the temperature averaged over the cross section is derived. The ion-beam diameter is assumed to be equal to the ring width. Solving this equation allows one to obtain the stationary temperature distribution along the ring-shaped target depending on the ion-beam, target, and cooling-gas parameters. Predictions are obtained for the rotating target to be installed at the DC-280 cyclotron. For an existing rotating target irradiated by an ion beam, our predictions are compared with the measured temperature distribution.

Collective acceleration of ions in picosecond pinched electron beams

Сharacteristics of intense electron–ion beams emitted by a high-voltage (280 kV) electron accelerator with a pulse duration of 200 ps and current 5 kA are studied. The capture phenomena and the subsequent collective acceleration of multi charged ions of the cathode material by the electric field of the electron beam are observed. It is shown that the electron–ion beam diameter does not exceed 30 µm therein in the case of lighter ions, and the decay of the pinched beam occurs at a shorter distance from the cathode. It is established that the ions of the cathode material Tin+ captured by the electron beam are accelerated up to an energy of ⩽10 MeV, and the ion fluence reaches 1017 ion cm−2 in the pulse. These ions are effectively embedded into the lattice sites of the irradiated substrate (sapphire crystal), forming the luminescent areas of the micron scale.

High-performance facility and techniques for high-precision machining of optical components by ion beams

The paper describes a high-performance facility for ion beam processing of the surface of optical elements. The facility is equipped with three technological ion sources, which allow working with inert or reactive gases, and a five-axis goniometer. Two sources (KLAN-103M and KLAN-163M) have a wide-aperture quasi-parallel ion beam and a third ion source with the focused ion beam (width of the output beam is Ø1–15mm by changing the diaphragm). For a focusing ion source an optimal diaphragm material (sapphire) and the Ar energy range (less than 400eV), which minimizes deposition on the surface of the workpiece the material sputtered from the edge of the diaphragm, are found. The concept of a movable workpiece has allowed realizing within one vacuum chamber three methods of ion beam surface treatment: aspherization, local shape errors correction and ion polishing. A detailed description of all the surface treatment methods is given. An algorithm for selecting the ion beam diameter and scanning steps for the local shape errors correction depending on the lateral dimension of the surface errors is proposed. The facility allows to produce an optical surface of any complex (convex/concave) shape, including higher-order aspheres with an asymmetrical profile and a diameter of up to 300mm, with a subnanometer precision of the surface shape and the effective roughness in the range of spatial frequencies q∈[2.5·10−2–6.0·101μm−1] down to σeff=0.14nm.

Improve optics fabrication efficiency by using a radio frequency ion beam figuring tool.

An ion beam with high removal rate and small diameter is expected in ion beam figuring. For an ion beam figuring tool, reducing the extraction grid opening is a feasible method to decrease the ion beam diameter, but the ion beam removal rate decreases at the same time. The ion beam removal rate depends much on the ion density in the ion source discharge room. The plasma in a hollow cathode (HC) ion source and a radio frequency (RF) ion source was simulated. The simulations suggested that the ion density in the RF ion source is higher than that of the HC one. Then, a RF ion source with an integrative matching network was developed and tested in this paper, where the ion beam removal rate reached up to 193 nm/min for 10 mm opening extraction grids.

Atomic Recombination in Dynamic Secondary Ion Mass Spectrometry Probes Distance in Lipid Assemblies: A Nanometer Chemical Ruler

The lateral organization of biological membranes is thought to take place on the nanometer length scale. However, this length scale and the dynamic nature of small lipid and protein domains have made characterization of such organization in biological membranes and model systems difficult. Here we introduce a new method for measuring the colocalization of lipids in monolayers and bilayers using stable isotope labeling. We take advantage of a process that occurs in dynamic SIMS called atomic recombination, in which atoms on different molecules combine to form diatomic ions that are detected with a NanoSIMS instrument. This process is highly sensitive to the distance between molecules. By measuring the efficiency of the formation of 13C15N- ions from 13C and 15N atoms on different lipid molecules, we measure variations in the lateral organization of bilayers even though these heterogeneities occur on a length scale of only a few nm, well below the diameter of the primary ion beam of the NanoSIMS instrument or even the best super-resolution fluorescence methods. Using this technique, we provide direct evidence for nanoscale phase separation in a model membrane, which may provide a better model for the organization of biological membranes than lipid mixtures with microscale phase separation. We expect this technique to be broadly applicable to any assembly where very short scale proximity is of interest or unknown, both in chemical and biological systems.

New type of capillary for use as ion beam collimator and air-vacuum interface

Glass capillaries offer a unique way to combine small diameter ion beam collimation with an air-vacuum interface for ambient pressure ion beam applications. Usually they have an opening diameter of a few microns, limiting the air inflow sufficiently to maintain stable conditions on the vacuum side. As the glass capillaries generally are quite thin and fragile, handling of the capillary in the experiment becomes difficult. They also introduce an X-ray background produced by the capillary wall material, which has to be shielded or subtracted from the data for Particle Induced X-ray Emission (PIXE) applications. To overcome both drawbacks, a new type of conical glass capillary has been developed. It has a higher wall thickness eliminating the low energy X-ray background produced by common capillaries and leading to a more robust lens. The results obtained in first tests show, that this new capillary is suitable for ion beam collimation and encourage further work on the capillary production process to provide thick wall capillaries with an outlet diameter in the single digit micro- or even nanometre range.

19aAE-10 Simulation of an ion beam diameter extracted into air through a large-bore metal capillary

19aAE-10 Simulation of an ion beam diameter extracted into air through a large-bore metal capillary

A realistic concept of a manned Mars mission with nuclear–electric propulsion

Based on state-of-the-art technique and recent developments, it would be feasible to send some cosmonauts to Mars around 2035. The key to this enterprise is the nuclear–electric in-space propulsion (NEP). In 2010, the development of the 1MWe nuclear space power plant as well as of the ion thrusters with the ion beam diameter of 50cm and specific impulse of 7000s was started at the Keldysh Research Center in Moscow. With regard to thrusters, the Keldysh Research Center cooperated with the Moscow Aviation Institute. According to our analysis, a cluster of ion thrusters (each of 50kW in power) with three 1MW reactors could propel a 250-tons vehicle with four cosmonauts on board to Mars and back.The mission architecture would be quite straightforward: the still unmanned spaceship will be assembled in the 800km LEO and then spiraled up by NEP into the 200,000km launch orbit. There, the chemical crew transport vehicle will arrive and dock. The interplanetary journey to Mars will require 337 days. On its arrival to Mars, the spaceship will spiral down into the 500km parking orbit. Then, a 65ton descent/ascent vehicle with three or four cosmonauts will leave the NEP vehicle and land. After 218 days, the excursion team will return to the mothership for the homebound trip. At the Earth approach, the cosmonauts will change to the crew transport vehicle, descend and land, whereas the burnt-out ship will be lost in space.It is true that one single spaceship is able to accomplish the mission. However, an international fleet of two or three manned ships together with a cargo ship would be recommendable, not only with regard to the volume of scientific results and a risk reduction, but also to demonstrate solidarity of mankind.

A new approach to express ToF SIMS depth profiling

We propose a new approach to express SIMS depth profiling on a TOF.SIMS‐5 time‐of‐flight mass spectrometer. The approach is based on the instrument capability to independently perform raster scans of sputter and probe ion beams. The probed area can be much smaller than the diameter of a sputter ion beam, like in the AES depth profiling method. This circumstance alleviates limitations on the sputter beam–raster size relation, which are critical in other types of SIMS, and enables analysis on a curved‐bottomed sputter crater. By considerably reducing the raster size, it is possible to increase the depth profiling speed by an order of magnitude without radically degrading the depth resolution. A technique is proposed for successive improvement of depth resolution through profile recovery with account for the developing curvature of the sputtered crater bottom in the probed area. Experimental study of the crater bottom form resulted in implementing a method to include contribution of the instrumental artifacts in a nonstationary depth resolution function within the Hofmann's mixing–roughness–information depth model. The real‐structure experiment has shown that the analysis technique combining reduction of a raster size with a successive nonstationary recovery ensures high speed of profiling at ~100 µm/h while maintaining the depth resolution of about 30 nm at a 5 µm depth. Copyright © 2015 John Wiley & Sons, Ltd.

Measurements of an ion beam diameter extracted into air through a large-bore metal capillary

To extract an ion beam into air, the technique using a single macro-capillary has been paid attention. We have expanded the bore of the metal capillary up to 500μm∅ inlet diameter to increase the beam intensity and have measured the intensity distributions of the extracted 3MeV proton beam. Furthermore, we have tilted the capillary angle and measured the intensity distributions of the ion beam. In this article, we will present the experimental results together with the simulation which takes the tilt angles of the capillary into account.

Improving the laser damage resistance of oxide thin films and multilayers via tailoring ion beam sputtering parameters

Ion beam sputtering is one of the widely used methods for manufacturing laser optical components due to its advantages such as uniformity, reproducibility, suitability for multilayer coatings and growth of dielectric materials with high packing densities. In this study, single Ta2O5 layers and Ta2O5/SiO2 heterostructures were deposited on optical quality glass substrates by dual ion beam sputtering. We focused on the effect of deposition conditions like substrate cleaning, assistance by 12cm diameter ion beam source and oxygen partial pressure on the laser-induced damage threshold of Ta2O5 single layers. Afterwards, the obtained information is employed to a sample design and produces a Ta2O5/SiO2 multilayer structure demonstrating low laser-induced damage without a post treatment procedure.

Development of characterization procedure of particulate matter pollution collected in immediate vicinity of urban residents

Advantage of using individual dust meters over traditional stationary particulate matter (PM) air pollution monitoring is evaluated. Data of air pollution levels obtained from the three municipal stationary monitoring stations were compared with data of individual dust meters SidePak AM 510. Results of a few control series of this comparison have indicated important differences between the mentioned two types of synchronised measurements. Taking into account that vast majority of time people spend indoors, one may expect that individual samplers better characterise exposition of any human being on the PM urban pollution. As a result, a new sampling procedure is proposed. It allows the collection of particulate matter in the immediate vicinity of human being: As collectors of the PM, we propose mobile phones, accompanying people whatever is their everyday activity. Namely, dust deposited in the inner parts of the used mobile phones is extracted and analysed. The procedure consists of bulk analysis performed with spark source mass spectrometry (SSMS) and depth profile analysis made by secondary ion mass spectrometry (SIMS). Exemplary results are presented of the particulate material deposited on high purity indium foils. Ion erosion is done with 5 keV Ar+, 150‐µm diameter ion beam scanned over 2 × 2.5 mm area. The analyser is equipped with Physical Electronics ion gun and QMA‐410 Balzers quadrupole mass spectrometer. Copyright © 2014 John Wiley & Sons, Ltd.

A new method to investigate the intense pulsed ion beam ablation of silica

Based on the energy conservation law and the Fourier law, a concise method is employed to build 2-dimensional difference heat conduction equations with appropriate boundary conditions. This method is useful in heat conduction simulation. A formula of the evaporation yield is derived to investigate the ability of every incident ion to evaporate silica through the heat effect. Then, using an argon ion beam as an example, the temperature and evaporation yield evolution of silica is simulated using the new heat conduction model and the evaporation yield formula. Under the calculated conditions of this work, when the evaporation of silica occurs, the evaporation yield increases continuously because the number of incident ions per second during one pulse decreases. At a given time, the evaporation yield decreases with the incident ion beam density because the increase of the number of evaporated silica molecules lags behind the increase of the incident ion number. The calculated results also show that the evaporation yield increases with incident ion beam diameter for a given time and ion beam density. In addition, the corresponding physical mechanism is analyzed theoretically.

Measurements of an ion beam diameter extracted into air through a glass capillary

To establish techniques for in-air materials analysis using a glass capillary, we studied the beam distribution extracted in air as a function of the distance between the exit of the capillary and the target. We measured three-dimensional intensity distributions of the extracted beams, and compared the observed results with the model calculation. The comparison showed that the glass capillary technique is designed to reduce a divergence of the beam extracted into the air by a beam-focusing effect.