GHz Electron Cyclotron Resonance Research Articles

Pulse height analysis using Si-pin diode of x-ray irradiated from a 2.45 GHz electron cyclotron resonance multicharged ion source

Production of multicharged ions is experimentally studied on an electron cyclotron resonance (ECR) source. The ECR zone for a microwave frequency of 2.45 GHz is formed at the bottom of a mirror trap. The x-ray spectra are measured by Si-pin diode detector in the various operating conditions. Available energy range of the x-ray measurement is several keV approximately several tens keV. Measurements are carried out at either line of sight including the ECR zone along the geometrical axis or at off-ECR zone from the side wall. The temperatures determined at both positions are about 2–3 keV from the observed spectrum with assuming nonrelativistic maxwellian plasma. The intensities of Ar Kα and bremsstrahlung radiation correlate to pressure and microwave power dependence of multicharged-ion production. But the dependence of the temperature is not clear. Therefore the multicharged-ion production largely depends on an abundance of high energy electrons rather than the change of the temperature of them in this energy region; and it is suggested that the emission profiles of the x-ray radiation peaks at the center of the mirror at the low pressure.

Development of 18 GHz electron cyclotron resonance ion source with high-voltage extraction configuration

An 18 GHz ECR ion source with high-voltage extraction configuration (NIRS-HEC) has been developed for the Heavy Ion Medical Accelerator in Chiba (HIMAC), National Institute of Radiological Sciences (NIRS). NIRS-HEC has a high extraction voltage of up to 60 kV in order to reduce the unwanted space charge effects at the extraction region. NIRS-HEC also has a strong magnetic field. A radial size of the plasma chamber is made as small as 40 mm, so that a sextupole field strength of 11 kG and an axial field strength of 12 kG are easily obtained. The experimental data show that a high extraction voltage is effective to realize the high beam intensity when the extraction current density is high. It is consistent with the computer calculations of the FUGUN code and TRAPCAD code.

Numerical simulation of highly charged ion production in RIKEN 18 GHz electron cyclotron resonance ion source

Numerical codes based on the model of ion confinement and losses in the electron cyclotron resonance (ECR) source have been applied to the mathematical simulation of krypton and xenon ion production in the 18 GHz ECR ion source at RIKEN. An equation of complete plasma energy is introduced to estimate the rf power of the ECR plasma heating. The final result of fitting is in reasonable agreement with the real experimental data for the Kr and Xe ion production in the source and used to estimate the main plasma parameters.

Beam bunching of the radioactive nuclear beam in a 6.4 GHz electron cyclotron resonance ion source

A single stage 6.4 GHz ECR ion source for an isotope separator on-line based radioactive nuclear beam facility at KEK-Tanashi, is under an on-line test for the effective production of Ne2+19 ions by using alpha beams from a cyclotron. Synchronized with the pulsed operation of heavy ion linacs, the millisecond beam bunching is now being performed to reduce the loss of radioactive ions in acceleration by using a pulsed-gating potential method. The highest beam intensity at 100 Hz and 20% duty factor reaches 60% of that obtained in a continuous-wave mode.

Production of intense beams of highly charged metallic ions from RIKEN 18 GHz electron cyclotron resonance ion source

We successfully produced intense beams of highly charged metallic ions from various kinds of organic metallic compounds by the metal ions from volatile compounds method and solid materials in RIKEN 18 GHz electron cyclotron resonance ion source (ECRIS) (e.g., 135 eμA of Fe11+, 80 eμA of Fe13+, 10 eμA of Os29+, and 1 eμA of Os37+). Using this ECRIS the ion confinement time of highly charged ions was determined under the pulsed mode operation.

Production of 3d metal ion electron cyclotron resonance plasmas and ion beams using volatile compounds

The metal ions from volatile compounds method was used to produce metal ion electron cyclotron resonance (ECR) plasmas and metal ion beams. In detail, the production of iron, nickel, and cobalt plasmas and beams on the 14.5 GHz ECR ion source of the TU Dresden is reported using ferrocene, nickelocene, and cobaltocene, respectively. Besides the detection of ion charge state distributions in extracted ion beams with an analyzing magnet first wavelength dispersive x-ray spectra of 3d cobalt metal ions were measured. Thereby, the based on atomic structure calculations analysis of x-ray satellites allows it to get information on the ion charge state spectrum of the ions inside the ECR plasma.

The development of an electron cyclotron resonance ion source for the heavy ion research facility in Lanzhou

A new working condition for an electron cyclotron resonance (ECR) source for the heavy ion research facility in Lanzhou (HIRFL) is reported. This condition is based on the full use of the secondary electrons injected into the source plasma near the extraction region of source cavity, and allows ion extraction from a denser plasma. A new magnetic field configuration which could move the Bmin of the mirror field towards the extraction region is also described. Using these technologies, our 10 GHz ECR source has delivered beam current of 320 and 80 eμA for the Ar9+ and Ar11+ ion, respectively. An ion extraction construction with a biased electrode was tested recently. Some details and the preliminary results are presented as well.

Determination of ion charge state distributions in krypton and cobalt electron cyclotron resonance plasmas by wavelength dispersive x-ray spectroscopy

Wavelength dispersive x-ray measurements on cobalt and krypton ions were presented to determine the ion charge state distribution (CSD) inside the electron cyclotron resonance (ECR) plasma of the 14.5 GHz ECR ion source of the TU Dresden. For clearly from the parent diagram lines separating x-ray satellites a comparison between calculated wavelength shifts and measured ones allows it to deduce the ion CSD of the analyzed ions. In the case of small line shifts (lower ionization states) a comparison with x-ray spectra derived from plasma modeling is done. By approximating the modeled spectra to the measured ones a most probable ion CSD was derived.

Production of Multicharged Os Ion Beams from Organic Metal Compounds Using a RIKEN 18 GHz Electron Cyclotron Resonance Ion Source

We successfully produced the multicharged osmium (Os) ions using metal ions from voatile compounds (MIVOC) method from a RIKEN 18 GHz electron cyclotron resonance ion source (ECRIS). Beam intensities of Os28+,33+ ions were 10 and 2.5 eµA at the RF power of 250 W, respectively.

Neoclassical islands on COMPASS-D

Neoclassical magnetic islands are observed to limit the achievable beta in COMPASS-D low collisionality single null divertor tokamak plasmas with ITER-like geometry (R0=0.56 m, B0=1.2 T, Ip=120-180 kA, k=1.6, epsilon =0.3). The limiting beta is typically well below that expected from ideal instabilities with maximum beta N in the range of 1.6 to 2.1. The plasma is heated with up to 1.8 MW of 60 GHz electron cyclotron resonance heating (ECRH) at the second harmonic with X mode polarization. The time history of the measured island width is compared with the predictions of neoclassical tearing mode theory, with good agreement between theory and experiment. The measured islands have a threshold width below which the mode will not grow. The density scaling of the point of onset of the measured instabilities is compared with two theories that predict a threshold island width for the onset of neoclassical tearing modes. Applied resonant helical error fields are used to induce islands in collisionality regimes wherein the neoclassical islands do not occur naturally, allowing the study of the behaviour of neoclassical tearing modes in this regime. The critical beta for the onset of neoclassical tearing modes is seen to be ~3 times higher in the naturally stable region. This observation is compared with the predictions of both threshold theories. A simple expression for the q scaling of the maximum achievable beta N in the presence of neoclassical tearing modes is derived on the basis of the assumption of a maximum allowable island width. The predicted q scaling of this beta limit is compared with data from a q scan, and the results are in good agreement

The new ECR ion source of the ATOMKI: A tool to generate highly charged heavy ion plasma and beam

Between 1993 and 1996 a 14 GHz electron cyclotron resonance (ECR) ion source has been designed and built in the ATOMKI. The ion source is aimed for the production of highly charged heavy ion beams from a wide range of the elements. One of the most important planned applications in the near future is its usage for low energy ion-atom collisions. This ion source is the first ECR ion source in Hungary and in Middle-Eastern Europe as well. The first plasma was successfully generated in February 1996 and the first extracted beam is expected in the fall of the year. This paper briefly reviews the history and progress of the ECR program and shows the ECR ion source itself. The results of some indirect plasma measurements (X-ray spectra) are shown and discussed.

Deposition of SiO 2 in integrated distributed electron cyclotron resonance microwave reactor

The deposition of dielectrics onto large areas is mostly carried out in traditional capacitively coupled 13.56 MHz RF plasma enhanced chemical vapour deposition reactors. Integrated distributed microwave 2.45 GHz electron cyclotron resonance (IDECR) configuration may be a possible alternative, if its potential advantages are realised. In this work we report on the results of SiO 2 deposition obtained with the IDECR system. Thin films of silica were deposited from the mixtures of SiH 4 with O 2 at different process conditions. Growth rates of silica up to 10 Å s −1 were obtained. Optical properties in UV-visible range were studied with spectroscopic phase-modulated ellipsometry. The first results suggest that films have high material quality and the deposition technique provides a broad process window. We study the influence of working pressure, power and gas composition on optical properties of SiO 2.

Basic experiments on in-situ magnetized boronization by electron cyclotron resonance discharges

Boronization based on electron cyclotron resonance (ECR) discharges is studied in a linear laboratory device under a parallel magnetic field of ∼ 0.1 T. A 2.45 GHz ECR discharge in a low-pressure helium decaborane mixture gives thin boron films localized on the walls near the gas inlet. In order to understand such film distributions, artificial deposition on plasma-exposed substrates in carried out. Two types of deposition processes are successfully discriminated in the magnetized plasma. One is neutral-induced deposition near the gas inlet and the other is ion-induced deposition in a downstream region. The latter plays a significant role in high-field high-density discharges. A simple scaling of deposition profile for each type of deposition is given along with its implication for achieving a deposition uniformity.

Characterization and recent modifications of a compact 10 GHz Electron Cyclotron Resonance (ECR) ion source for atomic physics experiments

A summary of recent modifications and developments of a compact ECR ion source where the magnetic field is produced by permanent magnets will be given in this paper. To improve the confinement of the plasma electrons the axial magnetic mirror ratio has been enhanced to 2.5. This results in a more efficient plasma heating at low microwave power levels and therefore ion currents up to 320 eμA could be extracted with a microwave power of less than 10 Watts. The maximum ion currents for different charge states and various gases obtained so far will be shown. Further interest arises from the fact that photons produced in an ECR plasma due to ionization and recombination processes can be used for spectroscopic applications in the VUV wavelength region between 10 and 80 nm.

Energy dispersive X-ray spectroscopy for ECR plasma diagnostics

Electron-ion bremsstrahlung spectra down to 4 keV emitted from plasmas of the 7.25 GHz electron cyclotron resonance (ECR) ion source of the Forschungszentrum Rossendorf and of the 14.5 GHz ECR ion source of the Technische Universitat (TU) Dresden were de-convoluted using a newly developed integration method. In the approximation of isotropy in velocity space this method yields the exact electron energy distribution function. The high energetic electrons are clearly separated into two Boltzmann distributed populations. Their densities and temperatures could be estimated. Higher frequencies of the microwave can increase the hot and warm electron densities by orders of magnitude. First results are obtained for the behaviour of this populations belonging to the mixture (argon — oxygen). Gas mixing increases the densities of these populations. The influence of the electron energy distribution function on X-ray line intensities is discussed.

Sputtering-assisted production of multicharged boron ions from solid material in a 2.45 GHz electron cyclotron resonance source

Multiply charged boron ions have been successfully produced and extracted from 2.45 GHz electron cyclotron resonance (ECR) ion source without gaseous feedstocks. A target material, solid-state boride, is immersed in an ECR plasma and dc bias voltages are applied to it. Argon is chosen for operating gas. The extracted boron ion current increases as the target approaches the ECR zone. The increase of boron atomic flux into the ECR zone enhances production of the boron ions. The enhancement is deduced from the dependence of boron ion current on solid angle subtended by the target at the ECR zone. The total boron ion current is equal to about 10% of the total argon one. The B2+ current is equal to 10%–20% of B+ one. The B3+ current can be detected at low microwave powers (∼150 W). The isotopes of boron are closely separated in natural abundance ratio.

A simple electron cyclotron resonance ion sourcea)

A simple, all permanent magnet, 2.45 GHz electron cyclotron resonance ion source has been developed for the production of stable beams of low charge state ions from gaseous feed materials. The source can produce ∼1 mA of low energy (3 kV) singly charged ion current in the 10−4 Torr pressure range. The source can also be operated in a more efficient low-pressure mode at an order of magnitude lower pressure. In this latter range, for example, the ionization efficiency of Ar is estimated to be 1% with charge states up to Ar8+ present. Operation in the low-pressure mode requires low power input (∼20 W). These features make the source especially suited for use with small accelerator systems for a number of applications including ion implantation, mass spectrometry, and atomic collision experiments where multiply charged ions are desirable. Design details and performance characteristics of the source are presented.

First results of a high-current electron cyclotron resonance proton source

A 2.45 GHz electron cyclotron resonance (ECR) ion source for producing a 100 mA H+ beam is under study. The microwave power is coupled through a quartz window and a water-cooled 90° waveguide bend in order to avoid the heating of the electrons backstreaming from the source. The ECR condition is obtained with dc magnetic coils. Preliminary results reported here show that a beam current density of 75 mA/cm2 can be extracted at 10 kV from a 3-mm-diam aperture, with 1.2 kW of microwave power at 1×10−3 mbar of hydrogen pressure. The proton fraction is 75% with an alumina-coated plasma electrode and 85% with a nitride coating.

Status report on the electron cyclotron resonance ion sources used for the production of radioactive ion beams at Louvain-la-Neuve

Two single-stage, 6 GHz electron cyclotron resonance (ECR) ion sources are currently in use at the ARENAS project at Louvain-la-Neuve. One of them is used to ionize radioactive elements to low charge states (1+ to 4+) before injection in the postaccelerator cyclotron. High intensity beams of 6He, 11C, 13N, 18Ne, and 19Ne are being produced. Recently the source has been adapted for the ionization of 18F and the first experiment with this beam has been performed. A second ECR source, almost identical to the first, is used in combination with the Leuven isotope separator on-line. It produces stable and radioactive beams at 50*q keV. Mass separated beams of 13N, 14O, and 15O can be produced using a high-temperature carbon target. An upgrade of this type of ECR source is now under construction. It consists mainly of increased magnetic fields and the capability for insertion of a heated cavity.

Magnet tests and status of the superconducting electron cyclotron resonance source SERSE

At Laboratorio Nazionale del Sud a superconducting 14.5 GHz electron cyclotron resonance (ECR) source will be used as injector for the K-800 superconducting cyclotron. The original project of its magnetic system has been upgraded by taking into account the results of the high B mode operation of the 6.4 GHz SC-ECRIS at MSU-NSCL and now the mirror field may achieve 2.7 T, which is much higher than the confining field of any other ECR source. The magnet design will allow us to operate in a wide range of magnetic configurations making it easy to tune the source. The status of the project will be outlined and the preliminary results of the tests of the superconducting magnets will be described. A brief description of the tests to be carried out on the source during the first period of operation on the test bench in Grenoble follows.