Penning Ion Source Research Articles

The increasing of H−current from Penning ion source with electrically biased metal hydride cathode

The possibility of the current increasing of negative hydrogen ions H− extracted in the longitudinal direction from gas-feed-free Penning type ion source with metal hydride cathode by the electric cathodes bias has been investigated. The separation of negative ions from the extracted flux of charged particles was performed by an electromagnetic filter, which consists of a magnetic coil for electron diverting and a grid under positive potential for positive ion reflection. The optimum for the effective extraction of H− ions has been determined. The H− ion current of 10 μA was obtained at an input power of 6 W.

Моды разряда пеннинговского ионного источника при импульсном и стационарном режиме питания

AbstractWe have analyzed the pressure dependences of the discharge and extracted currents for a Penning ion source (PIS) for continuous and pulsed power supplies. We have investigated the effect of voltage amplitude at the PIS anode, pulse repetition rate, and pulse duration on PIS amplitude–time and current–voltage characteristics. The ion source operation regimes and corresponding gas pressure ranges in which different modes of Penning discharge are realized have been determined.

A sharpening of the single crystal diamond tool by penning ion source

A sharpening of the single crystal diamond tool by penning ion source

28Si+ ion beams from Penning ion source based implanter systems for near-surface isotopic purification of silicon.

Modern computing technology is based on silicon. To date, a cost-effective and easy to implement method to obtain isotopically pure silicon is highly desirable for attaining efficient heat dissipation in microelectronic devices and for hosting spin qubits in quantum computing. We propose that it is possible to use a 28Si+ ion beam to obtain an isotopically pure near-surface region in wafer silicon. However, this requires a highly stable, high current, and isotopically pure 28Si ion beam. This work presents and discusses the instrumentation details and experimental parameters involved in generating this required ion beam. Silane is used as the precursor gas and is decomposed in a Penning ion source to generate a 28Si+ ion beam. The influence of key ion source parameters such as the gas flow rate, magnetic field strength, and anode voltage is presented. An isotopically pure 28Si+ ion beam with 10 ± 0.5 μA current on the target is obtained at the GNS Science 40 kV ion implanter. The beam was observed to be stable for at least 8 h and contains less than 700 ppm of other Si isotopes. This high current and high purity provides opportunities to explore efficient modification of the isotopic distribution in a native Si substrate at ambient temperature. The results highlight opportunities offered by using Penning ion source based low energy ion implanters for the synthesis of isotopically modified Si surface regions-a technique also applicable to other materials such as diamonds and diamond-like carbon.

Simulation and optimization of a negative hydrogen Penning ion source

The results of a Particle-In-Cell Monte-Carlo Collision simulation of a cold cathode Penning type ion source are presented. The source is designed to generate H− ions through the volume production process. Twenty-one important processes including electron and heavy particle collisions are introduced into the simulation. The main focus was the energy distribution of electrons which has a large effect on the H− production rate in the volume production. The dependence of the energy distribution of electrons on the axial magnetic field was investigated. The large sensitivity of the H− production rate to the energy distribution of electrons was measured. It was observed that for an anode with a 5 mm radius increasing the axial magnetic field in the range of 0.5–1.1 T results in the increase in the H− density almost by a factor of 14. In addition, it was found that the anode with a radius of 5 mm was the most efficient anode in H− production among the anodes with radii from 3 to 6 mm.

Measurement of the atomic ion fraction of ion emitted from a miniature penning ion source

Penning-type ion source performance for neutron generator applications is characterized partly by the atomic ion fraction, providing one path by which source performance can be improved for increased neutron yields. A miniature penning ion source has been fabricated to investigate the atomic ion fraction of deuterium plasma by a mass-energy analyzer. The discharge current and atomic ion fraction increase with the increase of anode voltage and pressure. Effects of electrode materials on discharge characteristics have been studied. The atomic ion fraction could increase about 2% of the original atomic fraction by Au cathode instead of steel cathode, and it could increase about 1% of the original atomic fraction by Al cathode. The results can provide useful information for improving source performance by selecting more suitable anode voltage, pressure and electrode material.

Deuterium Plasma Diagnosis in a Miniature Penning Ion Source by a Single Probe

The deuterium plasma parameters of a miniature Penning discharge ion source have been measured by a single probe. Electron temperature and electron density can be acquired from the I-V curves. The results show that electron temperature increases and electron density decreases with the probe tip departing from the centre of plasma area. Meanwhile, both electron temperature and electron density increase with increase in discharge current. Electron temperature is about 1.8 ~ 7.1 eV and electron density is about 2.7 χ 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">14</sup> - 3.7 χ 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">15</sup> m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-3</sup> , when the distance between the probe tip and the centre of plasma area varies from 1 to 6 mm. Electron temperature is about 5.7 - 12.5 eV and electron density is about 6.7 χ 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">14</sup> - 2.2 χ 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">15</sup> m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-3</sup> , when discharge current varies from 50 to 200 μA. The results can provide useful information for the design and operation of Penning ion sources.

Theoretical treatment of cold penning ion source with axial extraction

Theoretical treatment of cold penning ion source with axial extraction

Recent H- diagnostics, plasma simulations, and 2X scaled Penning ion source developments at the Rutherford Appleton Laboratory.

A vessel for extraction and source plasma analyses is being used for Penning H- ion source development at the Rutherford Appleton Laboratory. A new set of optical elements including an einzel lens has been installed, which transports over 80 mA of H- beam successfully. Simultaneously, a 2X scaled Penning source has been developed to reduce cathode power density. The 2X source is now delivering a 65 mA H- ion beam at 10% duty factor, meeting its design criteria. The long-term viability of the einzel lens and 2X source is now being evaluated, so new diagnostic devices have been installed. A pair of electrostatic deflector plates is used to correct beam misalignment and perform fast chopping, with a voltage rise time of 24 ns. A suite of four quartz crystal microbalances has shown that the cesium flux in the vacuum vessel is only increased by a factor of two, despite the absence of a dedicated cold trap. Finally, an infrared camera has demonstrated good agreement with thermal simulations but has indicated unexpected heating due to beam loss on the downstream electrode. These types of diagnostics are suitable for monitoring all operational ion sources. In addition to experimental campaigns and new diagnostic tools, the high-performance VSim and COMSOL software packages are being used for plasma simulations of two novel ion thrusters for space propulsion applications. In parallel, a VSim framework has been established to include arbitrary temperature and cesium fields to allow the modeling of surface physics in H- ion sources.

Corpuscular Diagnosis of the Plasma of Penning Ion Sources

The results of the studies of the energy distribution and atomic-molecular composition of the ions emitted from two Penning ion sources are presented. The transitions between different discharge modes, when the operating pressure and voltage on the anode are changed, are investigated. The energy spectra and mass-charge spectra are measured and the dependences of the fraction of atomic ions on the discharge parameters are determined.

Improvement of extracted ion beam from cold cathode Penning ion source

A direct current cold cathode Penning ion source is operated at the optimum parameters and pressure equal to 7×10−4 mmHg using argon gas. It consists of a copper cylindrical hollow anode and two movable molybdenum discs cathodes are placed symmetrically at two ends of the anode. Argon ion beam is extracted from the ion source by using extractor of different aperture diameter equal to 2.5, 3, 3.5, 4 and 4.5mm respectively. The extractor is placed at different distances from the ion exit aperture equal to 5, 10, 15 and 20mm respectively. It is found that at extractor aperture diameter equal to 3.5mm, ion exit aperture - extractor distance equal to 10mm and extraction potential applied on the extractor is equal to −500V, the optimum extracted ion beam current equal to 543 μA can be obtained. A comparison for Penning ion source without and with the extractor is made at the same optimum operating parameters, it is found that the extracted ion beam current from Penning ion source with the extractor increases about twice its initial value of Penning ion source without the extractor.

Study the optimum dimensions and operating parameters of Penning ion source

In this work, design and construction of a DC cold cathode Penning ion source is described. It consists of cylindrical hollow anode and two movable disc cathodes that are placed symmetrically at two ends of the anode. The electrical discharge and the output ion beam characteristics of the ion source are measured using argon gas. It is found that the optimum dimensions of anode–cathode distance, ion exit aperture diameter, and ion exit aperture – Faraday cup distance are equal to 8, 1.5, and 30 mm, respectively. The ion source efficiency was calculated at discharge current equal to 1.2 mA, different anode–cathode distances and pressures using argon gas. It is found that at anode–cathode distance equal to 8 mm and pressure equal to 7 × 10−4 mmHg, a maximum ion source efficiency equal to 27.1% can be obtained. The surface hardness of molybdenum specimen is measured after exposure to argon ion beam for two hours at pressure equal to 7 × 10−4 mmHg, discharge voltage equal to 3.5 kV, discharge current equal to 0.6 mA, and output ion beam current equal to 165 μA using argon gas. It is found that the surface hardness of molybdenum specimen is decreased by a factor of 24.2%.

Energy & mass-charge distribution peculiarities of ion emitted from penning source

The optimization of hydrogen Penning sources used, in particular, in plasma chemical processing of materials and DLC deposition, is still very important. Investigations of mass-charge composition of these ion source emitted beams are particular relevant for miniature linear accelerators (neutron flux generators) nowadays. The Penning ion source energy and mass-charge ion distributions are presented. The relation between the discharge current abrupt jumps with increasing plasma density in the discharge center and increasing potential whipping (up to 50% of the anode voltage) is shown. Also the energy spectra in the discharge different modes as the pressure and anode potential functions are presented. It has been revealed that the atomic hydrogen ion concentration is about 5-10%, and it weakly depends on the pressure and the discharge current (in the investigated range from 1 to 10 mTorr and from 50 to 1000 μA) and increases with the anode voltage (up 1 to 3,5 kV).

Magnetic field design for a Penning ion source for a 200 keV electrostatic accelerator

In this study, the structure of magnetic field for a Penning ion source has been designed and constructed with the use of permanent magnets. The ion source has been designed and constructed for a 200keV electrostatic accelerator. With using CST Studio Suite, the magnetic field profile inside the ion source was simulated and an appropriate magnetic system was designed to improve particle confinement. Designed system consists of two ring magnets with 9mm distance from each other around the anode. The ion source was constructed and the cylindrical magnet and designed magnetic system were tested on the ion source. The results showed that the ignition voltage for ion source with the designed magnetic system is almost 300V lower than the ion source with the cylindrical magnet. Better particle confinement causes lower voltage discharge to occur.

An experimental apparatus for Penning ion source research

An experimental apparatus and the research results of the discharge characteristics of a demountable Penning ion source are described. This apparatus is designed for both fundamental reflective-discharge investigations and the optimization of particular ion-source designs. The use of annular and grid anodes made it possible to visualize the discharge burning region and their structure depending on the pressure, the voltage, and the source geometry. Setting a hot cathode in the cathode unit allows the investigation of the nonself-sustained type of discharge and optimization of the ion-optical system. Replaceable cold cathodes (made of different materials) and a composed magnetic system significantly extend the possibilities of optimizing the ion-source constructions.

Study the effect of some parameters on the extracted ion beam from cold cathode Penning ion source

ABSTRACTA cold cathode Penning ion source was designed and operated at the optimumconditions. Its characteristics were determined using nitrogen and argon gases atpressure equal to 9×10-4 mmHg. Efficiency of this ion source was determinedusing nitrogen and argon gases. Also, ion source aspect ratio was determinedusing argon gas. The effect of negative voltage applied on Faraday cup usingargon gas was studied. Finally, a simple retarding electrostatic field energyanalyzer has been designed to determine the ion energy distribution.

The Penning Discharge Experimental Study and Its Simulation

The influence of the demountable Penning ion source electrodes geometry on the discharge characteristics and extracted ion current is investigated. The extracted currents, ignition potentials and the operational pressure ranges are compared at different anode heights and its arrangement relative to the discharge cell. The use of ring and mesh anodes has allowed to visualize the discharge burning areas and their structure versus the pressure, anode potential and cell geometry. Some PIC simulations of Penning discharge are made in the Vorpal code. The good correspondence between the simulated electron density and plasma glow areas on the photos is shown. The other one-particle simulation has shown that the magnetic field nonuniformity significantly affects the ignition and combustion discharge potentials.

Characterization of a cold cathode Penning ion source for the implantation of noble gases beneath 2D monolayers on metals: Ions and neutrals

Argon ion kinetic energy spectra at different discharge voltages (between 480 and 600 V) of a commercial cold cathode ion source IQP10/63 are reported. The high kinetic energy cut-off depends on the discharge voltage and the corresponding plasma potential due to excess positive charges which is found to be about 136 V. Exposure of single layer hexagonal boron nitride on rhodium to the beam of the ion source leads to the formation of nanotents, i.e., stable atomic protrusions. A positive bias voltage is applied to the target sample to block the positive ions produced by the ion source. However, application of a positive bias potential (800 eV), which is higher than the kinetic energy cut-off, still allows the formation of nanotents and its observation with scanning tunneling microscopy. This indicates that the ion source also produces neutral atoms with kinetic energies higher than the penetration threshold across a single layer of hexagonal boron nitride.

Recent developments of ion sources for life-science studies at the Heavy Ion Medical Accelerator in Chiba (invited).

With about 1000-h of relativistic high-energy ion beams provided by Heavy Ion Medical Accelerator in Chiba, about 70 users are performing various biology experiments every year. A rich variety of ion species from hydrogen to xenon ions with a dose rate of several Gy/min is available. Carbon, iron, silicon, helium, neon, argon, hydrogen, and oxygen ions were utilized between 2012 and 2014. Presently, three electron cyclotron resonance ion sources (ECRISs) and one Penning ion source are available. Especially, the two frequency heating techniques have improved the performance of an 18 GHz ECRIS. The results have satisfied most requirements for life-science studies. In addition, this improved performance has realized a feasible solution for similar biology experiments with a hospital-specified accelerator complex.

The mechanical design and simulation of a scaled H⁻ Penning ion source.

The existing ISIS Penning H(-) source is unable to produce the beam parameters required for the front end test stand and so a new, high duty factor, high brightness scaled source is being developed. This paper details first the development of an electrically biased aperture plate for the existing ISIS source and second, the design, simulation, and development of a prototype scaled source.