Autocollimation spectroscopy for fast hydrogenic ions

An R&D project of large scale ion beam equipment and processing is being carried out from 1986 till 1994. The project includes R&D of five ion beam systems and three material processes for surface modification. The five equipment R&D projects are:(1)High current metal ion beam system,(2)Integrated high current ion beam system,(3)Ionized multiple beam system with high deposition rate,(4)High energy ion beam system,(5)Gas-phase focused ion beam system.The three materials processing R&D projects are:(1)Glass surface modification,(2)Metal surface modification,(3)Low scattering multilayer film deposition. This paper reviews recent progress on development of the project. This work was conducted in the program: ’Advanced Material Processing and Machining System’ consigned to AMMTRA from the New Energy and Industrial Technology Development Organization, which is carried out under the Industrial Science and Technology Frontier Program enforced by the Agency of Industrial Science and Technology of Japan.

Production, acceleration and diagnostics of high intensity beams

Summary form only given. The MEVVA ion source has been intensively used to provide high current metallic ion beams for film deposition and material modification over the last two decades. At GSI it is using to produce a high particle current to fill up the heavy ion synchrotron SIS to its space charge limit. Many efforts have been made at GSI, to increase the beam brightness, to enhance the fraction of charge state 4 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">+</sup> for the design ion, to reduce the beam noise, and to improve the beam stability. To deliver the desired ion beam, a multi-aperture triode extraction system is used due to high mass to charge ratio of the design ion. In this paper, a fully three dimensional and interactive code KOBRA3-INP was used to investigate the behavior of the ion beam extracted from a high current MEVVA ion source and the effects of plasma density on extracted high current beam. The beam trajectory and space charge map in the extraction system are presented. Simulation shows that there exists a minimum divergence for the extracted ion beam at the plasma density of about 190 mA/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , which corresponds to the perveance matched condition. Furthermore, as the plasma density increases, the intensity of the extracted ion beam increases. If the experimental data with an extracted current of about 135-140 mA are used, the experimental data can be reproduced in the simulation with the longitudinal ion energy of 188 eV, the transverse ion energy of 100 eV, and the plasma density of 165 mA/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> under the assumption of the full space charge compensation.

A new high current ion implanter "LUXiON" has been developed for semiconductor production. LUXiON implant several ion species to 300 mm silicon wafer by vertical long ion beam and horizontal mechanical scan wafer handling system. We describe the tool outline, beam result and implant results.

The high power ion beams used in the next generation thermonuclear fusion reactors require high current negative ion beams accelerated to high energy, with high efficiency. One way to meet these requirements is to merge multiple low current density H− beamlets into a single high current beam. The feasibility of a high current merging preaccelerator was demonstrated in this experiment by merging 19 beamlets of H− ions distributed over a circular area 80 mm in diameter from a Japan Atomic Energy Research Institute negative ion source. H− ions were extracted at a current density exceeding 10 mA/cm2 at the ion source which operates at 0.13 Pa (1 mTorr), with a low arc power density (70 V×250 A). Spherically curved grids (with built-in magnetic electron suppression) were used in the preaccelerator to focus the extracted beamlets into a single 104 mA, 100 keV beam. The merged beam has a diameter of 23 mm and a converging angle of ±30 mrad at the beam envelope. The rms emittance of the 104 mA merging beam was 1.00 π mrad cm, which is a condition acceptable to the electrostatic quadropole accelerator for further acceleration.

Two years ago during the 1975 Particle Accelerator Conference in Washington, we reported the development of an intense negative ion magnetron source, capable of extracting short pulsed negative ion beams of several hundred mA. For most particle accelerators these pulsed beams are more than adequate, but for efficient neutral injector systems in future fusion reactors multi-ampere dc negative ion beams are required.

22 A beam production of the uniform negative ions in the JT-60 negative ion source

Plasma shape control by pulsed solenoid on laser ion source

The temperature control system of the large-size plasma grid has been developed to realize the long pulse production of high-current negative ions for JT-60SA. By using this prototype system for the JT-60SA ion source, 15 A negative ions has been sustained for 100 s for the first time, which is three times longer than that obtained in JT-60U. In this system, a high-temperature fluorinated fluid with a high boiling point of 270 degree Celsius is circulated in the cooling channels of the plasma grids (PG) where a cesium (Cs) coverage is formed to enhance the negative ion production. Because the PG temperature control had been applied to only 10% of the extraction area previously, the prototype PG with the full extraction area (110 cm × 45 cm) was developed to increase the negative ion current in this time. In the preliminary results of long pulse productions of high-current negative ions at a Cs conditioning phase, the negative ion production was gradually degraded in the last half of 100 s pulse where the temperature of an arc chamber wall was not saturated. From the spectroscopic measurements, it was found that the Cs flux released from the wall might affect to the negative ion production, which implied the wall temperature should be kept low to control the Cs flux to the PG for the long-pulse high-current production. The obtained results of long-pulse production and the PG temperature control method contributes the design of the ITER ion source.

This paper presents an extensive numerical study of heating of thin solid carbon foils by 1.4 MeV/u uranium ion beams to explore the possibility of using such a target as a charge stripper at the proposed new Gesellschaft für Schwerionenforschung high energy heavy–ion linac. These simulations have been carried out using a sophisticated 3D computer code that accounts for physical phenomena that are important in this problem. A variety of beam and target parameters have been considered. The results suggest that within the considered parameter range, the target will be severely damaged by the beam. Thus, a carbon foil stripper does not seem to be a reliable option for the future Gesellschaft für Schwerionenforschung high energy heavy–ion linac, in particular, at FAIR design beam intensities.

Ion source and injector experiments at the HIF/VNL

This report describes the results of a study of arrays of up to sixteen quadrupoles in a single cryostat surrounded by an induction accelerator that is used for accelerating high current heavy ion beams for fusion. Each quadrupole in the array can have a gradient of 72 T/m, when the quadrupole has a warm bore diameter of 90 mm. An array of sixteen quadrupoles can be made to fit into a round cryostat vacuum vessel with a diameter of 850 mm. If the number of quadrupoles in the array is reduced to nine, the outer diameter of the cryostat is 700 mm. It is proposed that the quadrupole array be conduction cooled using either a 4 K cryocooler or two phase liquid helium in pipes around the magnet array. The two-phase helium can be supplied to a string of multi-bore quadrupoles using a large refrigerator.

An Implantation System for MeV-mA Ion-Beams

The damage and erosion of plasma-facing components (PFCs) due to extremely high heat loads and particle bombardment is a key issue for the nuclear fusion community. Currently high current ion and electron beams are used in laboratories for simulating the behaviour of PFC materials under ITER-like conditions. Our results indicate that high-power nanosecond lasers can be used for laboratory simulation of high heat flux PFC material degradation. We exposed tungsten (W) surfaces with repetitive laser pulses from a nanosecond laser with a power density ∼ a few GW cm−2. Emission spectroscopic analysis showed that plasma features at early times followed by intense particle emission at later times. Analysis of laser-exposed W surface demonstrated cracks and grain structures. Our results indicate that the typical particle emission features from laser-irradiated tungsten are consistent with high-power particle beam simulation results.

Metal vapour vacuum arc source ion implantation as a surface treatment technique for industrial tool bits