摘要:

The principles, construction, and performance of the MINIMAFIOS electron cyclotron resonance ion source (ECRIS) are reviewed. The source can operate either pulsed, with pulse width of >50 ms, or cw, with 1011fully stripped light ions per second and much higher amounts of lower charge state ions. The source has excellent reliability and reproducibility. It has acceptable emittance and energy dispersion. The manner of operation and adjustment of the source is very simple since it depends only on the two parameters: gas feed and rf power injected. In addition, metallic ions can be produced directly. ECRIS is well suited for injection into heavy ion accelerators and for atomic physics. Its high ion fluxes in a quasicontinuous regime are useful for numerous other applications and open new fields for scientific research with multiply charged ions. Thus, more and better sources are desired. New ideas have been proposed and new sources have been built or are under construction. We present the latest performance data of MINIMAFIOS for gaseous elements as a reference for evaluating the performance of new ECRIS in various laboratories. For metallic ions we need more experimental results in order to establish basic data references.

ISSN:0034-6748    

DOI:10.1063/1.1138145

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

The detailed description and performance characteristics of a microwave ion source are presented. This ion source utilizes an internally tuned, single‐mode (or selective multimode) cylindrical cavity applicator to focus and match microwave energy into a disk‐shaped discharge zone. The combination of mode focus control and variable, internal cavity matching allows the efficient operation and beam extraction over a wide range of pressures, powers and gaseous inputs. Experimental measurements of ion beam current versus accelerating voltage and input microwave power in xenon and oxygen gas are presented. Ion source specific energy and mass utilization versus experimental variables are also determined. The experimental performance demonstrates the ability of this ion source to extract an ion beam with a well matched, stable, and continuous operation over a wide range of input gases, low pressures, and over input gas flow rates in excess of 100 to a few sccm. Double Langmuir probe measurements in xenon gas indicate high degrees of ionization, and electron and ion concentrations in excess of 100 critical densities in the microwave discharge zone. This ion source has many potential uses such as spacecraft electric propulsion, material ion beam processing, and neutral beam ion sources.

ISSN:0034-6748    

DOI:10.1063/1.1138146

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

The design, construction, and performance of an electron impact heated hydrogen dissociation oven for use in producing an atomic hydrogen gas target for ion–atom collision experiments are described. This novel design utilizes an electron beam focused by a spherical lens system to heat the oven to temperatures in excess of 2400 K. High dissociation fractions are found with cell pressures ≥5 mTorr. The compact design allows placement of an electron spectrometer close to the interaction region (length ∼1.5 cm), as well as direct measurement of the oven temperature by means of an optical pyrometer. The electron beam produces magnetic fields ∼40 mG ∼1 cm from the center of the interaction region. These low magnetic fields offer distinct advantages compared to low‐voltage, high‐current oven designs when observing relatively low‐energy electrons ejected in ion–atom collisions.

ISSN:0034-6748    

DOI:10.1063/1.1138147

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

A high‐heat‐flux target has been developed for intercepting multimegawatt, multisecond neutral beams at Oak Ridge National Laboratory (ORNL). Water‐cooled copper swirl tubes are used for the heat transfer medium; these tubes exhibit an enhancement in burnout heat flux over conventional axial flow tubes. The target consists of 126 swirl tubes [each 0.95 cm in outside diameter (o.d.) with 0.16‐cm‐thick walls and ≊1 m long] arranged in a V shape and inclined with respect to the beam axis. In tests with the ORNL long‐pulse ion source (13×43‐cm grid), the target has handled up to 3‐MW, 30‐s beam pulses with no deleterious effects. The peak power density was estimated at ≊15 kW/cm2normal to the beam axis (>5 kW/cm2maximum on tube surfaces). The water flow rate through the tubes was 0.33 l/s (5.2 gal/min) per tube (axial flow velocity=11.6 m/s) with a corresponding pressure drop of 1.14 MPa (165 psi). To date, the target has absorbed an estimated 25 000 full‐power (≊3 MW) pulses for a cumulative time of ≊100 000 beam seconds without failure. Other potential applications for swirl tube technology in the fusion area include plasma limiters, divertor collector plates, rf launchers, and Faraday shields.

ISSN:0034-6748    

DOI:10.1063/1.1138148

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

The geometrical efficiency is calculated for a radioactive source‐moderator assembly, which is often used for the production of slow‐positron beams, and comparisons are made between a cylinder source, touching the circumference of the moderator, and a spot source, facing the center of the moderator. It is shown that higher beam intensity and brightness can be obtained with the cylinder source in most practical situations.

ISSN:0034-6748    

DOI:10.1063/1.1138149

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

A compact magnetic energy analyzer designed for the measurement of electron energies in the range from 20 keV through 1.5 MeV is described. The simple device, based on the semicircular focusing principle, is constructed from a high induction permanent magnet enclosed in a soft iron case. The design and operation of the analyzer in pulsed electron beam devices are discussed.

ISSN:0034-6748    

DOI:10.1063/1.1138520

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

A new spectrographic system has been developed and calibrated in this laboratory for the absolute spectrometry of high‐intensity pulsed x‐ray sources in the 100–10 000‐eV region. This spectral region is analyzed with fixed elliptically curved crystals and molecular or sputtered‐or‐evaporated multilayers of 2d values in the 3–160‐A range. Twin channels are utilized for simultaneous time‐integrated photographic recording and for time‐resolved x‐ray streak camera recording. Absolute calibrations of the elliptical analyzers, of the photographic film, and of the gold and CsI transmission photocathodes have been made using monoenergetic, cw laboratory x‐ray sources. The overall transmission characteristics of the spectrograph have also been determined. The instrument has been designed for mounting through a pneumatically controlled high‐vacuum valve onto a 4‐in. port of a 1‐m‐diameter source chamber and includes an appendage, high‐vacuum, sputter‐ion prepumping station. The initial dynamic testing and application of this new spectrographic system has been on the University of Rochester’s LLE 24 laser beam OMEGA source facility.

ISSN:0034-6748    

DOI:10.1063/1.1138150

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

A Bragg crystal spectrometer, utilizing a microchannel plate coupled to optical film as the detection medium, has been constructed for use in soft x‐ray spectroscopy. The sensitivity of this intensified gated camera to x‐rays has been compared directly with standard x‐ray film using a calibrated x‐ray source. In addition, this high gain, intensified crystal spectrograph (ICS) has been used in an experiment to precisely measure spectral coincidences between x‐ray lines in laser‐generated plasmas, thus identifying candidates for photoresonant x‐ray lasing schemes in the 10–21‐A˚ region. At long wavelengths the ICS was able to obtain useful data on faint lines in a single laser shot, rather than the multiple shots required by an adjacent spectrograph using x‐ray film. It also allowed line coincidences to be verified by a new technique utilizing split disk targets. The design and construction of the ICS and results obtained with it are compared with those obtained with standard x‐ray film.

ISSN:0034-6748    

DOI:10.1063/1.1138151

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

A retarding‐field differential‐output energy prefilter has been optically matched to a quadrupole mass spectrometer to produce a high‐performance secondary ion quadrupole mass spectrometer. The sample area was designed to be field free to allow for sample charge compensation and to prevent secondary ion trajectories from being affected by electric fields. Design considerations for optically matching the energy prefilter to the quadrupole mass filter (QMF) are discussed. The overall transmission of the instrument was 1.8×10−4at a mass resolution of 100M/&Dgr;M (1–100 amu range) for copper and 1.7×10−5at a mass resolution of 400M/&Dgr;M(10–250 amu range) for tungsten.

ISSN:0034-6748    

DOI:10.1063/1.1138152

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

A cryofracture device has been developed for freeze‐cleaving cultured cells grown on a polished substrate wafer. The fracture is made under liquid nitrogen and results in specimens suitable for ion microscopic analysis to reveal the intracellular elemental distribution. In performing this operation the nutrient media is also removed, precluding any need of prewashing the specimen and introducing any contamination or loss in subcellular ion concentrations. The design and performance of this device are described.

ISSN:0034-6748    

DOI:10.1063/1.1138153

出版商:AIP    

年代:1985

数据来源: AIP