摘要:

A long lifetime ion source with plasma cathode has been developed for use in ion implantation. In this ion source, a plasma of a nonreactive working gas serves as a cathode in place of a thermionic tungsten filament used in the Freeman ion source. In an applied magnetic field, the plasma is convergent, i.e., filamentlike; in zero magnetic field, it turns divergent and spraylike. In the latter case, the plasma exhibits a remarkable ability when the working gas has an ionization potential larger than the feed gas. By any combination of a working gas of either argon or neon and a feed gas of AsF5or PF5, the lifetime of this ion source was found to be more than 90 h with an extraction voltage of 40 kV and the corresponding ion current density 20 mA/cm2. Mass spectrometry results show that this ion source has an ability of generating a considerable amount of As+and P+ions from AsF5and PF5, and hence will be useful for realizing a fully cryopumped ion implanter system. This ion source is also eminently suitable for use in oxygen ion production.

ISSN:0034-6748    

DOI:10.1063/1.1139559

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

The characteristics of the magnetized plasma obtained in a modified double‐plasma device are presented. Primary ionizing electrons are produced by filament discharges in multipole devices located on either end of a magnetized plasma column. A very uniform magnetized plasma is produced in the column with a relatively small number of filaments by using coils to counterbalance the fringing field near the filaments. The obtained plasma is well suited for a large variety of wave experiments. The noise is maintained at a low level and the afterglow measurements reveal a very efficient confinement of the ionizing electrons, with a decay time of 0.2 ms.

ISSN:0034-6748    

DOI:10.1063/1.1139516

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

A specialized method has been developed to maximize the two‐dimensional detail obtained from two perpendicular bolometer arrays. The technique relies on the assumption that poloidal variation exists only near the plasma surface. The cross section is divided into appropriate zones and the emittance is reconstructed by a numerical method. The position, intensity, and width of large features are clearly displayed. A marfe is tracked as it drifts around the plasma and evolves into a radiating shell detached from the limiter. A central peak, plus inner‐wall radiating layer, plus a marfe appear in a high‐density case reached by pellet injection.

ISSN:0034-6748    

DOI:10.1063/1.1139557

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

The Plasma‐Materials Interactions Test Facility (PMITF) recently designed and constructed at Oak Ridge National Laboratory (ORNL) is an electron cyclotron resonance microwave plasma system with densities around 1011cm−3and electron temperatures of 10–20 eV. The device consists of a mirror cell with high‐field‐side microwave injection and a heating power of up to 0.8 kW (cw) at 2.45 GHz. The facility will be used for studies of plasma‐materials interactions and of particle physics in pump limiters and for development and testing of plasma edge diagnostics.

ISSN:0034-6748    

DOI:10.1063/1.1139558

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

A time‐resolved measurement of an impulsive ion source has been carried out by developing a detector consisting of a magnetic energy analyzer and a microchannel plate (MCP) with multianodes. A method to calibrate the electron multiplication factor of the MCP for charged particles using a solid‐state nuclear track detector (SSNTD) is presented. The method has been successfully used for the energy analysis of the deuteron beam produced by the plasma focus. The method is applicable not only for deuterons but also for any other energetic charged particles.

ISSN:0034-6748    

DOI:10.1063/1.1139560

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

A nozzle valve having a programmable opening time has been realized and tested. Its working principle differs from those used before in similar devices. In a preliminary version, the valve has been shown to be able to deliver gas pulses having a rise time of about 45 &mgr;s and a variable time length from 250 &mgr;s (FWHM) to continuum. It can also be operated as a beam chopper with frequency in the range 0–270 Hz and a variable duty factor. The valve does not generate either rf disturbances or appreciable current spikes in the ground network. It is a simple construction device and does not require a critical setup.

ISSN:0034-6748    

DOI:10.1063/1.1139561

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

A method is described for performing electron‐impact ionization time‐of‐flight mass spectrometry in a molecular beam apparatus. It provides a convenient means for optimizing the performance of pulsed or continuous nozzle sources and can be used in conjunction with laser excitation. Mass spectra are produced either as analog waveforms or in a high repetition rate ion counting mode. The device can also be operated as a fast ionization gauge for time‐resolved detection of pulsed beams.

ISSN:0034-6748    

DOI:10.1063/1.1139562

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

A commercial, external image intensifier unit has been adapted to an imaging atom‐probe mass spectrometer. The image intensifier can be operated in a pulsed mode to obtain time‐gated (i.e., species specific) images while simultaneously recording time‐of‐flight mass spectra. This capability was used to calibrate the amplitudes of rhodium, tungsten, and neon ion signals which appear in imaging atom‐probe mass spectra. The signal amplitudes were found to be directly proportional to the number of imaged ions over a range of amplitudes covering three orders of magnitude. The proportionality constant was found to be nearly the same for doubly charged rhodium and triply charged tungsten ions, but significantly different for neon ions. The constant was not sensitive to variations of ∼30% in the applied voltage (i.e., ion energy).

ISSN:0034-6748    

DOI:10.1063/1.1139563

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

A new method for two‐dimensional imaging x‐ray spectrometer is introduced. The optical system consists of a microchannel plate as a large‐aperture collimator and a flat Bragg‐type diffractor. This method can be applied to radiation covering from VUV to hard x ray. The feasibility has been demonstrated by using x rays of two different energies and a LiF crystal.

ISSN:0034-6748    

DOI:10.1063/1.1139564

出版商:AIP    

年代:1987

数据来源: AIP

摘要:

A scanning laser acoustic microscope (SLAM) is described. The SLAM achieves a resolution of about 10 &mgr;m and is capable of imaging subsurface features at depths up to several millimeters, using appropriate reconstruction algorithms. The various components of the apparatus, both acousto‐optical and electronic, are described. A major feature of the SLAM is a digital data‐acquisition system capable of storing and processing the complex acoustic field in images with 256×256‐pixel resolution. An array processor enables most floating‐point operations to be completed in a few seconds. Examples of acoustic images obtained from a test sample are presented.

ISSN:0034-6748    

DOI:10.1063/1.1139565

出版商:AIP    

年代:1987

数据来源: AIP