Intense highly charged ion beam production is essential for high-power heavy ion accelerators. A novel movable Vlasov launcher for superconducting high charge state electron cyclotron resonance ion source has been devised that can affect the microwave power effectiveness by a factor of about 4 in terms of highly charged ion beam production. This approach based on a dedicated microwave launching system instead of the traditional coupling scheme has led to new insight on microwave-plasma interaction. With this new understanding, the world record highly charged xenon ion beam currents have been enhanced by up to a factor of 2, which could directly and significantly enhance the performance of heavy ion accelerators and provide many new research opportunities in nuclear physics, atomic physics, and other disciplines.

Processes of the secondary electron emission (SEE) from the walls are included into the Numerical Advanced Model of Electron Cyclotron Resonance Ion Sources (NAM-ECRIS). It is found that SEE strongly influences electron confinement time and ion production. With the modified model, we observe reactions of the source to changes in a gas flow into the source and in an injected microwave power. The source performance with scaling the hexapole magnetic field is investigated. The calculated tendencies are close to the experimental observations.

The three-dimensional particle-in-cell model NAM-ECRIS is used for investigation of how the DECRIS-PM Electron Cyclotron Resonance Ion Source is reacting to changes in the source magnetic configuration. The accent is made on changes in the magnetic field at the magnetic trap center, the minimum-B value. It is calculated that the optimal normalized value of the field is 0.8, close to the experimental observations. The reasons for existence of the optimum are discussed. It is observed that the electron energies are increasing with the increased minimum-B values due to enhanced confinement of the energetic electrons in the plasma. Bumps in energy spectra of the radially lost electrons are observed and explained to be due to nonadiabatic losses of electrons.

The three-dimensional NAM-ECRIS model is applied for studying the metal ion production in the DECRIS-PM Electron Cyclotron Resonance Ion Source. Experimentally measured extracted ion currents are accurately reproduced with the model. Parameters of the injection of metal vapors into the source are optimized. It is found that the axial injection of the highly directional fluxes allows increasing the extracted ion currents of the highly charged calcium ions by factor of 1.5. The reason for the gain in the currents is formation of internal barrier for the ions inside the plasma, which increase the ion extraction and production efficiency. Benefits of injecting the singly-charged calcium ions instead of atoms are discussed.

The Numerical Advanced Model of Electron Cyclotron Resonance Ion Source (NAM-ECRIS) is applied for studies of the physical processes in the source.Solutions of separately operating electron and ion modules of NAM-ECRIS are matched in iterative way such as to obtain the spatial distributions of the plasma density and of the plasma potential.Results reveal the complicated profiles with the maximized plasma density close to the ECR surface and on the source axis.The ion-trapping potential dips are calculated to be on the level of ~(0.01-0.05)V being located at the plasma density maxima.The highly charged ions are also localized close to the ECR surface.The biased electrode effect is due to an "electron string" along the source axis formed by reflection of electrons from the biased electrode and the extraction aperture.The string makes profiles of the highly charged ions more peaked on the source axis, thus increasing the extracted ion currents.

Further progress in the development of electron cyclotron resonance (ECR) ion sources (ECRISs) requires deeper understanding of the underlying physics. One of the topics that remains obscure, though being crucial for the performance of the ECRIS, is the electron energy distribution (EED). A well-developed technique of measuring the EED of electrons escaping axially from the magnetically confined plasma of an ECRIS was used for the study of the EED in an unstable mode of plasma confinement, i.e., in the presence of kinetic instabilities. The experimental data were recorded for pulsed and CW discharges with a room-temperature 14 GHz ECRIS at the JYFL accelerator laboratory. The measurements were focused on observing differences between the EED escaping from stable and unstable plasmas. It was found that nonlinear phenomena alter the EED noticeably. The electron losses are enhanced in both unstable regimes, with two-frequency heating suppressing the instabilities. It has been shown earlier that two-frequency heating boosts the ECRIS performance presumably owing to the suppression of instabilities. We report the observed changes in EED introduced by the secondary frequency in different regimes, including an off-resonance condition, where the secondary frequency is lower than the minimum frequency satisfying the resonance condition for cold electrons at the magnetic field minimum. Finally, we suggest an experimental method of qualitative evaluation of the energy distribution of electrons confined in the magnetic trap using a method of measuring energy distribution of lost electrons during the plasma decay in pulsed operation of the ion source.

Since the early 1970s, attempts to synthesize Super Heavy Elements (SHE) have been made in many laboratories around the world. One of the main requirements of these experiments is a sufficiently large dose of target irradiation, which should be increased with a decrease in the reaction cross section. In this regard, the capacities of ion sources play an important role for the successful synthesis of SHE. At the FLNR JINR, the discovery and investigation of the new region of super heavy nuclei were based on fusion reactions of 48Ca with 238U–249Cf target nuclei. In these experiments, a technique for the production of metallic 48Ca was developed. The operation mode of the ECR ion source was set to optimize the intensity of 48Ca ions and attain maximum ionization efficiency. Because of the heaviest target for experiments on synthesis of SHE in heavy ion reactions is 249Cf, so further progress in the synthesis of elements with Z > 118 requires the production of intense beams of accelerated neutron enriched isotopes, such as 50Ti, 58Fe, and 64Ni.

Three-dimensional numerical model is developed and applied for studies of physical processes in Electron Cyclotron Resonance Ion Source. The model includes separate modules that simulate the electron and ion dynamics in the source plasma in an iterative way. The electron heating by microwaves is simulated by using results of modelling the microwave propagation in the plasma by the COMSOL Multiphysics software. Extracted ion currents and other parameters of the source are obtained for different gas flows into the source. It is observed that the currents are strongly influenced by ion transport in transversal direction induced by the plasma potential gradients. Impact of some special techniques on the source performance is investigated. Magnetic field scaling is shown to reduce the ion losses during their movement toward the extraction aperture, as well as use of the aluminum chamber walls and mixing of the working gas with helium.

Charge-breeding processes in Electron Cyclotron Resonance Ion Sources are numerically simulated by using the target helium plasma parameters obtained with NAM-ECRIS code. Breeding efficiency is obtained as a function of 1+ ion injection energy for some alkali ion beams. Time dependencies of extracted ions are calculated; typical times for reaching saturation in currents are in the range of few tens of milliseconds. Role of charge-exchange processes in breeding of ions is discussed. Recycling of ions on the source walls is shown to be important.

Ion extraction from DECRIS-PM source is simulated by using initial distributions of ions at the extraction aperture obtained with NAM-ECRIS code. Three-dimensional calculations of plasma emissive surface are done and ions are traced in the extraction region. The ion beam profiles show strong aberrations due to shape of plasma meniscus; hollow beam features are reproduced, as well as changes in profiles for different focusing conditions.

Free parameters of Numerical Advanced Model of ECRIS (NAM-ECRIS) are selected such as to reproduce the experimental charge-state-distribution of the extracted argon ions for the DECRIS-PM source tuned to produce the maximized Ar8+ currents. Using these fixed parameters, we calculate the extracted currents for Kr, Xe and Bi ions in mix with oxygen, for Ca in mix with helium, and for pure O and He plasmas. Comparison is made with the experimental data, good correspondence is observed.

Super-heavy-element factory is under development at the Flerov Laboratory of-Nuclear Reactions, JINR, Dubna. The factory will include DC-280 cyclotron, which will be equipped with two 100 kV high voltage platforms. A high charge state all-permanent magnet 14 GHz ECRIS - DECRIS-PM has been designed and fabricated to provide intense multiple charge state ion beams. The request for the source is a production of medium mass ions (A/q=4 divided by 7) such as Ca-48(8+). The conceptual design of DECRIS-PM is presented. During the first tests, the source shows a good enough H performance for the production of medium charge state ions (such as 900 e mu A Ar8+, 550 e mu A Ar9+, 200 e mu Ar11+, A 160 e mu A Kr-15+, etc.).

Electron dynamics in Electron Cyclotron Resonance Ion Source is numerically simulated by using Particle-In-Cell code combined with simulations of the ion dynamics. Mean electron energies are found to be around 70 keV close to values that are derived from spectra of X-ray emission out of the source. Electron life time is defined by losses of low-energy electrons created in ionizing collisions; the losses are regulated by electron heating rate, which depends on magnitude of the microwave electric field. Changes in ion confinement with variations in the microwave electric field and gas flow are simulated. Influence of electron dynamics on the afterglow and two-frequency heating effects is discussed.

The particle-in-cell Monte Carlo collisions code NAM-ECRIS is used to simulate the electron cyclotron resonance ion source (ECRIS) plasma sustained in a mixture of Kr with O-2, N-2, Ar, Ne, and He. The model assumes that ions are electrostatically confined in the ECR zone by a dip in the plasma potential. A gain in the extracted krypton ion currents is seen for the highest charge states; the gain is maximized when oxygen is used as a mixing gas. The special feature of oxygen is that most of the singly charged oxygen ions are produced after the dissociative ionization of oxygen molecules with a large kinetic energy release of around 5 eV per ion. The increased loss rate of energetic lowly charged ions of the mixing element requires a building up of the retarding potential barrier close to the ECR surface to equilibrate electron and ion losses out of the plasma. In the mixed plasmas, the barrier value is large (similar to 1 V) compared to pure Kr plasma (similar to 0.01 V), with longer confinement times of krypton ions and with much higher ion temperatures. The temperature of the krypton ions is increased because of extra heating by the energetic oxygen ions and a longer time of ion confinement. In calculations, a drop of the highly charged ion currents of lighter elements is observed when adding small fluxes of krypton into the source. This drop is caused by the accumulation of the krypton ions inside plasma, which decreases the electron and ion confinement times.

Transverse phase-space distributions of low-energy ion beams extracted from ECR ion sources often show higherorder effects caused by ion-optical aberrations. Understanding these effects is mandatory to keep emittance growth and the resulting beam losses in low-energy beam transport lines under control. We present results of an experimental and theoretical study of beam extraction and transport in the AGOR injection line at KVI. Particle tracking simulations have been performed of a multi-component neon ion beam extracted from an ECR ion source to calculate 4D phase-space distributions at various positions along the beam line. The simulations compare well with beam profile and emittance measurements.

The specialized heavy ion cyclotron DC-110 has been designed and created by the Flerov Laboratory of Nuclear Reactions of Joint Institute for Nuclear Research for scientifically industrial complex “BETA” placed in Dubna (Russia) [1]. DC-110 cyclotron is intended for accelerating the intense Ar, Kr, Xe ion beams with fixed energy of 2.5 MeV/nucleon. The commissioning of DC110 cyclotron has been carried out at the end of 2012. The project parameters of the ion beams have been achieved. During commissioning of cyclotron, the vertical displacement of the beam at the last orbits and at the extraction channel was revealed. The calculations and experiments have shown that the reason of this displacement is the radial component of magnetic field at the median plane of the cyclotron, which appears because of asymmetry of the magnet yoke. Correction of the vertical displacement of the beam has been achieved by creating an asymmetry of current distribution in the main coil of the cyclotron electromagnet. EXPERIMENTAL TESTING OF THE EXTRACTED BEAM POSITION AND DIMENSION Commissioning of the DC-110 cyclotron has been done at the end of 2012. During the experimental testing of the cyclotron, the extracted beam position and dimension was analyzed. The beam tracks on the constructed elements of extraction system has shown that the beam at the last orbits and during the extraction has a vertical displacement. The extraction system consist of electrostatic deflector and passive magnetic channel. At the Fig. 1 the beam track at the deflector entrance, R=894 mm, has 3 mm of vertical displacement above median plane. Figure 1: The beam track at the deflector entrance. At the magnetic channel exit the beam track already has shown 5 mm of vertical displacement. At the distance of 1.1 meter after magnetic channel, in the extracted beam transport line, the luminophore probe is placed. The beam track at the probe has shown 16 mm of vertical displacement and aperture losses, Fig. 2. Figure 2: The beam track at the luminophore probe. ESTIMATION OF MAGNET AXIAL ASYMMETRY INFLUENCE ON BEAM DYNAMIC AT EXTRACTION AREA The main reason of the vertical displacement of the beam at the last orbits and at the extraction channel is the radial component of magnetic field, Br, on the median plane of the cyclotron. Br component appears because of vertical asymmetry of the magnet yoke. Figure 3: The model of asymmetric yoke of DC-110 cyclotron magnet. WEPPT008 Proceedings of Cyclotrons2013, Vancouver, BC, Canada ISBN 978-3-95450-128-1 338 C op yr ig ht © 20 13 C C -B Y3. 0 an d by th e re sp ec tiv e au th or s Beam Dynamics Beam Transport At the case of DC-110 cyclotron, the reason of this asymmetry was the difference of the upper and lower axial holes in the yoke. The upper hole is used for axial injection system. The lower hole not used and was closed with iron in the magnet pole to prevent the vacuum losses. 1.63 1.64 1.65 1.66 1.67 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 R, m B , T 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8

A detailed experimental and simulation study of the extraction of a 24 keV He(+) beam from an ECR ion source and the subsequent beam transport through an analyzing magnet is presented. We find that such a slow ion beam is very sensitive to space-charge forces, but also that the neutralization of the beam's space charge by secondary electrons is virtually complete for beam currents up to at least 0.5 mA. The beam emittance directly behind the extraction system is 65 π mm mrad and is determined by the fact that the ion beam is extracted in the strong magnetic fringe field of the ion source. The relatively large emittance of the beam and its non-paraxiality lead, in combination with a relatively small magnet gap, to significant beam losses and a five-fold increase of the effective beam emittance during its transport through the analyzing magnet. The calculated beam profile and phase-space distributions in the image plane of the analyzing magnet agree well with measurements. The kinematic and magnet aberrations have been studied using the calculated second-order transfer map of the analyzing magnet, with which we can reproduce the phase-space distributions of the ion beam behind the analyzing magnet. Using the transfer map and trajectory calculations we have worked out an aberration compensation scheme based on the addition of compensating hexapole components to the main dipole field by modifying the shape of the poles. The simulations predict that by compensating the kinematic and geometric aberrations in this way and enlarging the pole gap the overall beam transport efficiency can be increased from 16% to 45%.

This paper reports on work performed during the last two years to improve the performance of the KVI-AECR ion source, which is used as an injector for the AGOR cyclotron. We have installed stainless-steel screens at the injection and extraction sides and an additional collar around the extraction aperture resulting in better plasma stability and an increase of extracted ion currents. Source tuning is aided by continuously observing the visible light output of the plasma through the extraction aperture with a CCD camera. We now routinely extract 700 μA of O 6+ ions and 50 μA of Pb 27+ ions. Source optimization is supported by extensive computational modelling of the ion transport in the lowenergy beam line and measuring the transverse emittance of the extracted ion beam with a pepperpot emittance meter. These efforts have shown that second-order aberrations in the analyzing magnet lead to a significant increase of the effective beam emittance. Work is underway to compensate these aberrations.