摘要:

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. ©1998 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1148549

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

A prototype surface ionization source coupled with a fixed-geometry extraction electrode system was commissioned on the Isotope Separator Accelerator (ISAC) ion source test stand at TRIUMF. The suitability of the ion source and extraction system for use in the ISAC facility was determined by a series of emittance measurements of the extracted beams. The test stand optics were successfully commissioned using the prototype ion source; emittance measurements of the mass-separated beams demonstrated that second- and third-order beam aberrations (introduced by the magnetic dipole mass separation) could be corrected by the use of multipole electrostatic optics elements. An upper limit of the root-mean-square-energy spread (2 eV) was deduced from the emittance measurements. Emittance measurements were performed at beam energies of 10–50 keV, as well as for ion masses ranging fromLi+toRb+,to demonstrate the feasibility of the prototype for a variety of beam energies and masses. ©1998 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1148656

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

A new-concept plasma grid, named frame-cooling-type plasma grid, was developed for a long pulse operation of a cesium-seeded volumeH−ion source. The frame-cooling-type plasma grid was tested using a long pulseH−ion source. The grid has a kind of bellows structure that acts as thermal insulator to keep the surface temperature at an optimum value forH−ion production. It was confirmed that the temperature was kept at over 250 °C, an optimum temperature for the cesium effect, in steady-state operations with the plasma grid cooled by room-temperature water. Using the plasma grid, a maximumH−ion beam of 40 keV, 600 mA(16 mA/cm2)for a long pulse operation of 90 s was generated successfully. ©1998 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1148657

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

Plasma potentials are measured in a 2.45 GHz electron cyclotron resonance (ECR) multicharged ion source. Both axial and radial potential profiles are determined for an argon plasma by using a Langmuir probe at various pressures. Multicharged ions up toAr12+are observed in the extracted beam. The plasma potentials are positive with respect to the plasma chamber wall and are on the order of several tens of volts. The values in profile measurements of the plasma potential are consistent with the spatial averaged values obtained by ion beam measurement. Along the mirror axis the plasma potential, the electron temperature, and density increase as the ECR zone is approached, and are roughly flat or hollow near the ECR zone. The radial profiles are loosely peaked or flat at the position off the ECR zone, and asymmetrical or hollow near the ECR zone. Due to some serious problems for the probe measurement, the plasma potential is deduced by several methods and the density is estimated from ion saturation currents. ©1998 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1148658

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

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 ArK&agr;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. ©1998 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1148659

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

To find the residual gas pressure(P)suitable for operating a thermal positive ion source, a beam of molecule (MX) such as LiH, NaCl, or TlI was directed with a constant flux(N≈1013 molecules cm−2 s−1)onto a surface of Re or W heated to a constant temperature(T≈1000–2100 K),and the ion current (∼10−10–10−8 A,corresponding to∼10−7–10−5 A cm−2) ofM+was measured as a function ofP(∼1×10−7–5×10−5 Torr),which was increased by the introduction of air. These data thus obtained were analyzed to determine the ionization efficiency(&bgr;+)of MX and the work function(&fgr;+)of each surface. Analysis of the relation amongP,T,&bgr;+,and&fgr;+indicates that to produce a strong ion beam from MX, selection ofP≈1×10−6 Torris recommended for keeping&bgr;+as large as possible in a wide range ofT≈1100–1400 Kwhere&fgr;+>6.3 eVis maintained by adsorption ofO2,and hence where&bgr;+≈1even for TlX is attained, but to detect rapidly a neutral beam of MX in kinetic studies of very rapid reactions,P≈1×10−5should be selected together with∼1600 K,thereby keeping&fgr;+≈5.8 eV,and hence, yielding&bgr;+⩾0.9for MX so long as the ionization energy ofMis less than∼5.2 eV.©1998 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1148660

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

The purpose of this experiment is to improve the optics of an intenseH−negative-ion beam, to be used in future Tokamaks. The emittance diagnostic has been installed in the experimental setup INCA, to perform an optimization of a negative-ion injector preaccelerator. The first stage of this work consists of testing the operation of the electric-sweep scanner, to measure the beam current in the two-dimensional-phase space and to investigate the diagnostic performances. In addition to the measurement ofH−angles, we can scan the angles of the fastH+created along the beam in the transport region and test the efficiency of the electron magnetic trap installed in the second accelerator grid (extraction electrode). We also observe the presence of a neutral component. This analyzer not only provides a diagnostic of the beam divergence but also improves of the knowledge of the beam components. We studied two accelerator configurations. The first one permitted to obtain an optimal beam optics under 15 keV. Then the accelerator geometry was modified to ensure a higher optimum high voltage. We will show several experimental results performed with two accelerator configurations. ©1998 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1148661

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

The requirements for negative ion sources designed for accelerator mass spectrometry (AMS) are, e.g., a high and stable beam current, a high efficiency, a low memory effect, and a quick system for switching between different samples. For the AMS program at the Lund 3 MV Pelletron tandem accelerator a new caesium sputtering source was constructed and installed a few years ago. Some new mechanical features of the source, as well as tests of how well the requirements are fulfilled are reported. ©1998 American Institute of Physics. 

ISSN:0034-6748    

DOI:10.1063/1.1148751

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

Broad ion beam mass filters working by a mass dependent radio-frequency acceleration of ions are a new approach to generate mass filtered broad ion beams with diameters of about 300 mm in the future. The ions are extracted from an ion source by a two grid extraction system with holes of 2.5 mm diameter followed by seven hole grids with the radio-frequency mass separator. A basic question for future successful use of this system for ion implantation is the impurity generation by sputtering of ions on the walls of the hole grids. Therefore the amount of neutral and charged impurities in the ion beam was investigated by mass spectroscopic beam analysis. It is shown that the relative amount of charged impurities in the ion beam is less than5×10−4,and the amount of neutral impurities from sputtering is smaller than impurities created by ion-molecule interactions of the ion beam with the residual gas (basic pressure10−8 mbar). ©1998 American Institute of Physics.

ISSN:0034-6748    

DOI:10.1063/1.1148662

出版商:AIP    

年代:1998

数据来源: AIP

摘要:

A 45° parallel-plate energy spread analyzer has been designed and built for the ISAC project at TRIUMF. It features an energy resolution of⩽0.04&percent;and a spectrometer constant ofk=1.29.Nineteen 0.1 mm by 10 mm metal guard frames with 1 M&OHgr; resistors are used to equalize the electric field in the analyzer to an order of⩽0.5&percent;.Electric field simulation is done by a codePOISSON. This article describes the design of the analyzer. Preliminary experimental results are also presented. ©1998 American Institute of Physics. 

ISSN:0034-6748    

DOI:10.1063/1.1148663

出版商:AIP    

年代:1998

数据来源: AIP