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Jul 1995

Volume 66, Issue 7, pp. 3729-4003

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Accurate polarization interferometer

Vincenzo Greco, Giuseppe Molesini, and Franco Quercioli

Rev. Sci. Instrum. 66, 3729 (1995); http://dx.doi.org/10.1063/1.1145429 (6 pages) | Cited 13 times

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A polarization interferometer which measures optical path differences with improved accuracy control is presented. The approach makes use of four signals in quadrature, computing the phase with an algorithm insensitive to laser power drifts. Experimental results of the interferometer’s performance are given under laser warmup conditions, and with long‐term monitoring of optical path differences. © 1995 American Institute of Physics.
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07.60.Ly Interferometers

A power‐stable CO2 laser with ceramic resonator frame

T. Bartosch and M. März

Rev. Sci. Instrum. 66, 3735 (1995); http://dx.doi.org/10.1063/1.1145430 (3 pages)

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A CO2 laser with a resonator frame made of low expansion ceramics has been developed to provide superior passive stability properties. High stiffness, low specific weight, and very good electric insulation properties recommend ceramic as an attractive material for many laser applications. The long‐term power stability of a first prototype was better than ±0.44% measured over 15 min, the short‐term stability was better than ±0.24%. Both values were achieved without any active stabilization technique, without damping of external vibrations, and with a non‐temperature‐controlled coolant. With a new switch mode power supply without ballast resistor a wall‐plug efficiency of about 14% has been achieved under quasi‐sealed‐off conditions. The specific laser output power was about 20 W/m at a gas pressure of 18.5 mbar and a gas mixture He:N2:CO2=75:15:10+5.5% Xe. © 1995 American Institute of Physics.  
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42.55.Lt Gas lasers including excimer and metal-vapor lasers

Low‐temperature micro‐photoluminescence using confocal microscopy

Jun‐ichi Kasai and Yoshifumi Katayama

Rev. Sci. Instrum. 66, 3738 (1995); http://dx.doi.org/10.1063/1.1145431 (6 pages) | Cited 15 times

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We describe an optical setup for low‐temperature micro‐photoluminescence measurements using confocal microscopy. The spatial resolution of the setup was estimated by observing photoluminescence images of a luminescent line formed in a cleaved face of a quantum‐well crystal. A high spatial resolution of 0.55 μm was obtained at a 457.9 nm excitation wavelength. Measurements of photoluminescence excitation spectra are also possible with a high spatial resolution of less than 1 μm. As an application of low‐temperature micro‐photoluminescence measurements, photoluminescence images of a dot array comprising buried quantum wells have been obtained. These images show the distribution due to emissions from single dots with diameters down to 0.3 μm. © 1995 American Institute of Physics.
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07.79.-v Scanning probe microscopes and components
78.55.-m Photoluminescence, properties and materials

Photon correlation system for fluorescence lifetime measurements

C. G. Morgan, J. G. Murray, and A. C. Mitchell

Rev. Sci. Instrum. 66, 3744 (1995); http://dx.doi.org/10.1063/1.1145432 (6 pages) | Cited 1 time

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The construction and testing of a dual‐channel photon correlator is reported for the frequency domain imaging of fluorescence lifetimes using photon‐counting detection. A light source modulated at radio frequency excites fluorescence, which is detected using an imaging single‐photon detector. After discrimination, single‐photon events are processed in parallel by the correlation circuit, the purpose of which is to allow both the mean phase delay and the demodulation of fluorescence to be calculated relative to a reference signal derived from the modulated excitation source. Outputs from the correlator are integrated in a computer, resulting in accumulation of images which have been statistically filtered by sine and cosine transforms, and which can be manipulated within the computer to generate a resultant image where contrast depends on fluorescence lifetime rather than fluorescence intensity. © 1995 American Institute of Physics.
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82.80.Ms Mass spectrometry (including SIMS, multiphoton ionization and resonance ionization mass spectrometry, MALDI)
87.64.K- Spectroscopy

A closed loop scheme for phase‐sensitive fluorometry

Venkatesh Vadde and Vivek Srinivas

Rev. Sci. Instrum. 66, 3750 (1995); http://dx.doi.org/10.1063/1.1145433 (5 pages) | Cited 4 times

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A phase‐sensitive detection technique for measuring fluorescence lifetime has the advantage that the measurement is independent of the intensity of the detected fluorescence signal which is usually a function of several properties of the sample and the environment. However, lifetime measurements require bulky and expensive instrumentation and are more suited to the laboratory. In this paper we report on a low cost, closed loop scheme applied to a fiber optic oxygen sensor. The sensor has all the advantages of lifetime‐based sensors as well as the virtue of being small, compact, robust, and economical. © 1995 American Institute of Physics.  
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07.57.-c Infrared, submillimeter wave, microwave and radiowave instruments and equipment
07.60.-j Optical instruments and equipment

A soft x‐ray spectrometer for resonant inverse photoemission

P. Weibel, M. Grioni, C. Hêche, and Y. Baer

Rev. Sci. Instrum. 66, 3755 (1995); http://dx.doi.org/10.1063/1.1146441 (7 pages) | Cited 5 times

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We describe the concept and the performances of a new tunable soft x‐ray inverse photoemission (IPES) spectrometer. The instrument is based on a variable‐geometry Bragg spectrograph, and it can be operated with minor modifications over a wide range of photon energies (600<hν<4000 eV). It was originally designed for IPES measurements of cerium compounds at the Ce M5(3d5/2→4f,hν=883 eV) absorption edge, where the Ce 4f IPES cross section is resonantly enhanced. Such resonant IPES (RIPES) spectra, now routinely performed by this instrument, are 10–100 times more sensitive to the Ce 4f states than conventional x‐ray bremsstrahlung spectra, with a comparable energy resolution (ΔE∼600 meV). We plan to exploit the wide tunability of the spectrometer to perform RIPES measurements of other correlated materials, namely at the Cu L2,3(2p→d,hν=930 and 950 eV) edge in the high‐Tc superconductors. © 1995 American Institute of Physics.
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07.85.Nc X-ray and γ-ray spectrometers

Relative calibration of photodiodes in the soft‐x‐ray spectral range

M. Anton, M. J. Dutch, and H. Weisen

Rev. Sci. Instrum. 66, 3762 (1995); http://dx.doi.org/10.1063/1.1145434 (8 pages) | Cited 7 times

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A method of obtaining a relative calibration of Si photodiodes for the spectral range of soft x rays (1–30 keV) is presented. A simple mathematical model of the p‐n diode is adopted which allows the response to be described in terms of a small set of parameters. The diffusion length as well as the thickness of a dead layer below the front surface of the diodes are obtained from measurements of angular dependences of the photoinduced current. It is shown that a precise characterization of the diode response and an accurate relative calibration can be obtained using this method. However, it was found that the presence of a dead layer a few tenths of a micrometer thick can pose severe restrictions on the use of planar diode arrays in x‐ray tomography systems where uniformity of response is crucial. The method has been applied to the diode arrays equipping the x‐ray tomography system built for the TCV tokamak, a magnetic fusion research device. © 1995 American Institute of Physics.
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85.60.Dw Photodiodes; phototransistors; photoresistors
52.70.La X-ray and γ-ray measurements

Computer vision based morphometric characterization of neural cells

Luciano da F. Costa

Rev. Sci. Instrum. 66, 3770 (1995); http://dx.doi.org/10.1063/1.1145435 (4 pages) | Cited 4 times

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This article reports on the application of computer vision techniques, implemented on an IBM PC‐compatible machine, as a means of obtaining morphometric characterization of neural cells. The features considered include projection polar histograms, orientation polar histograms, and the determination of the convex hull of dendritic (or axonal) arborizations. As will be discussed in this work, the Hough transformation technique has proven to be of great help for the determination of all the above‐mentioned parameters. Two actual application examples respective to the analysis of retinal ganglion cells are also presented and discussed. © 1995 American Institute of Physics.
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42.30.Tz Computer vision; robotic vision
87.80.-y Biophysical techniques (research methods)

Automatic temperature‐controlled helium‐vapor cryostat for atom‐probe field‐ion microscopy studies

G. P. E. M. Van Bakel, D. A. Shashkov, and D. N. Seidman

Rev. Sci. Instrum. 66, 3774 (1995); http://dx.doi.org/10.1063/1.1145436 (3 pages) | Cited 3 times

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An automatic temperature control mechanism was fabricated from readily available components and installed on an existing continuous flow helium‐vapor cryostat as part of an atom‐probe field‐ion microscope. This control system eliminates tedious manual adjustment of the vapor flow rate. It is shown that the time needed to cool the cryostat from room temperature to a cryogenic temperature is reduced from 3 to 1 h. Within the 40–80 K range changes in the setpoint temperature are accommodated within 10 min. The temperature stability is better than 0.1 K. © 1995 American Institute of Physics.
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07.20.Mc Cryogenics; refrigerators, low-temperature detectors, and other low-temperature equipment
07.78.+s Electron, positron, and ion microscopes; electron diffractometers

Superconductor imaging surface magnetometry

David B. van Hulsteyn, Albert G. Petschek, Edward R. Flynn, and William C. Overton

Rev. Sci. Instrum. 66, 3777 (1995); http://dx.doi.org/10.1063/1.1145437 (8 pages) | Cited 10 times

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The presence of superconducting surfaces in the vicinity of current sources may be interpreted in terms of image theory. This concept has both experimental and theoretical practicality. Experimentally, sensing coils for magnetic detection, when placed near such surfaces, perform in a gradiometric fashion. In order to explain this effect explicitly, a theoretical treatment of the magnetic fields in the presence of superconducting surfaces and coils is presented. Expressions are derived for planar and spherical geometries that approximate practical experimental situations. These expressions may be used to predict the expected gradiometric response of a coil as a function of the positions of the source and coil relative to the surface. © 1995 American Institute of Physics.
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07.55.Ge Magnetometers for magnetic field measurements
87.63.Hg Thermography

In situ testing and calibrating of z‐piezo of an atomic force microscope

Joseph Fu

Rev. Sci. Instrum. 66, 3785 (1995); http://dx.doi.org/10.1063/1.1145438 (4 pages) | Cited 12 times

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By scanning a slightly tilted, smooth surface with an atomic force microscope (AFM), it is possible to obtain hysteresis loops which contain information on the nonlinearity and hysteresis in the z axis of the AFM’s piezoelectric actuator. A 15% variation in vertical sensitivity was revealed by this PZT tube during vertical scans ranging in amplitude between 0.4 and 2.5 μm, which could result in a high level of uncertainty in a vertical measurement. Therefore a separate vertical measuring system or a correction scheme is required for a precise and accurate measurement. © 1995 American Institute of Physics.
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07.79.Lh Atomic force microscopes

Method for the calibration of atomic force microscope cantilevers

John E. Sader, Ian Larson, Paul Mulvaney, and Lee R. White

Rev. Sci. Instrum. 66, 3789 (1995); http://dx.doi.org/10.1063/1.1145439 (10 pages) | Cited 280 times

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The determination of the spring constants of atomic force microscope (AFM) cantilevers is of fundamental importance to users of the AFM. In this paper, a fast and nondestructive method for the evaluation of the spring constant which relies solely on the determination of the unloaded resonant frequency of the cantilever, a knowledge of its density or mass, and its dimensions is proposed. This is in contrast to the method of Cleveland et al. [Rev. Sci. Instrum. 64, 403 (1993)], which requires the attachment of masses to the cantilever in the determination of the spring constant. A number of factors which can influence the resonant frequency are examined, in particular (i) gold coating, which can result in a dramatic variation in the resonant frequency, for which a theoretical account is presented and (ii) air damping which, it is found, leads to a shift of ∼4% in the resonant frequency down on its value in a vacuum. Furthermore, the point of load on the cantilever is found to be extremely important, since a small variation in the load point can lead to a dramatic variation in the spring constant. Theoretical results that account for this variation, which, it is believed will be of great practical value to the users of the AFM, are given. © 1995 American Institute of Physics.
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07.79.Lh Atomic force microscopes

An inexpensive STM conversion to a BEEM

Rong Zhang, Robert Stefaniuk, and Douglas G. Ivey

Rev. Sci. Instrum. 66, 3799 (1995); http://dx.doi.org/10.1063/1.1145440 (3 pages) | Cited 1 time

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Ballistic electron emission microscopy (BEEM) is a relatively new technique enabling spectroscopic investigation of subsurface interface structures and electronic properties. BEEM is a direct, nondamaging method with nanometer spatial resolution. In this paper, an inexpensive modification to a conventional scanning tunneling microscope, converting it to a BEEM, is presented. BEEM performance is significantly affected by the preamplifier and the low‐pass filter, which is used to improve the signal‐to‐noise ratio. The system is tested on a thin Au metallization to (100) Si. © 1995 American Institute of Physics.  
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07.79.Cz Scanning tunneling microscopes

The use of scanning conduction microscopy to probe abrasion of insulating thin films

J. T. Dickinson, L. C. Jensen, K. H. Siek, and K. W. Hipps

Rev. Sci. Instrum. 66, 3802 (1995); http://dx.doi.org/10.1063/1.1145441 (5 pages) | Cited 4 times

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The use of scanning force microscopy (SFM) to probe wear processes at interfaces is of considerable interest. A simple modification of the SFM which allows one to make highly spatially resolved measurements of conductivity changes produced by abrasion of thin insulating films on metal substrates is presented here. The technique is demonstrated on fluorocarbon polymer thin films deposited on stainless‐steel substrates. © 1995 American Institute of Physics.
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07.79.Lh Atomic force microscopes
81.40.Pq Friction, lubrication, and wear

Parallel, multichannel energy and angle resolving electrostatic electron analyzer

Peter Downie, David J. Reynolds, and Ivan Powis

Rev. Sci. Instrum. 66, 3807 (1995); http://dx.doi.org/10.1063/1.1145442 (12 pages) | Cited 7 times

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A new charged particle analyzer offering parallel and multichannel detection of a range of emitted energy and angle is described. Simultaneous multiplex detection of both these variables is achieved with the use of a two‐dimensional position sensitive detector. The instrument is so arranged that angular information is recovered from the azimuthal coordinate, and energy from the radial coordinate of each detected particle. The instrument is based upon the original ‘Bessel Box’ design of Allen and co‐workers and shares many of the favorable characteristics of that analyzer. General theoretical principles are considered and assessed, and then the actual performance of a specific device, fabricated for use in an angle resolved UV photoelectron‐photoion coincidence experiment is reported. Simple in situ control of the operational mode of the instrument is described and demonstrated with the prototype, allowing convenient selection of the most effective compromise between resolution and bandwidth. © 1995 American Institute of Physics.
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41.85.Qg Particle beam analyzers, beam monitors, and Faraday cups

Quasidivergency‐free extraction of a slow positron beam from high magnetic fields

D. Gerola, W. B. Waeber, M. Shi, and S. J. Wang

Rev. Sci. Instrum. 66, 3819 (1995); http://dx.doi.org/10.1063/1.1145443 (7 pages) | Cited 5 times

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In a hybrid slow positron beam, extraction of the positrons from the magnetic field (∼1 T for the PSI beam) to field‐free space is a necessary operation. A theoretical and experimental demonstration is given which shows that the following proposed beam extraction method works as predicted: magnetic transport of the slow positrons down to field strengths of ∼100 G and passage through an aperture grid of ∼10 cm diameter in a field termination shield followed by some brightness enhancement stages. The simulation and measurement of the magnetic‐field distributions along the beam axis show a steep drop down of the field from ∼100 G to a few gauss within 1 cm of shield thickness and a quasiuniform spreading of the transverse field strength across the grid opening. Measurement of transmission and divergency (transverse energy) of the beam exiting the extraction aperture confirmed theoretical estimations and ray tracing calculations for the aperture design used to be of the order of 75% and 20 eV, respectively. These data as a function of field strength and beam energy are used for optimization of the final extraction aperture design (≳85% transmission) to be used in the PSI high intensity beam facility. © 1995 American Institute of Physics.  
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41.75.Fr Electron and positron beams
41.85.Ar Particle beam extraction, beam injection

Performance of a solenoid‐driven pulsed molecular‐beam source

L. Abad, D. Bermejo, V. J. Herrero, J. Santos, and I. Tanarro

Rev. Sci. Instrum. 66, 3826 (1995); http://dx.doi.org/10.1063/1.1145444 (7 pages) | Cited 18 times

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The characteristics of a commonly used pulsed valve for the production of free jets and molecular beams are analyzed in detail. Special attention is paid to the formation of gas pulses providing a quasisteady flow during a certain time interval within the pulse duration, and to the estimation of a scaling parameter (effective diameter) for the description of the flow field. The adequacy of this effective diameter is checked by performing time‐of‐flight measurements on molecular beams of Ne, N2, and CH4, and stimulated Raman spectra on free jets of N2 and CH4. © 1995 American Institute of Physics.
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07.77.Gx Atomic and molecular beam sources and detectors

Laser‐driven flow reactor as a cluster beam source

M. Ehbrecht, H. Ferkel, V. V. Smirnov, O. M. Stelmakh, W. Zhang, and F. Huisken

Rev. Sci. Instrum. 66, 3833 (1995); http://dx.doi.org/10.1063/1.1145445 (5 pages) | Cited 21 times

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A novel technique for the production of expansion‐cooled cluster beams from materials with low vapor pressure is presented. The clusters are produced in a flow reactor from gas phase reactants by aggregation of CO2‐laser‐induced decomposition products. By introducing a conical nozzle into the reaction zone, they are extracted into a molecular beam apparatus and analyzed with a time‐of‐flight mass spectrometer. Depending on the type of CO2‐laser employed, the source can be operated in the pulsed or continuous mode. The generation of carbon and silicon clusters is demonstrated by decomposing gaseous C2H2 and SiH4, respectively. The laser‐driven cluster course is also employed to generate fullerenes and nanosized silicon particles. © 1995 American Institute of Physics.  
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07.77.-n Atomic, molecular, and charged-particle sources and detectors
61.46.-w Structure of nanoscale materials

Vibrational spectroscopy of clusters using a ‘‘magnetic bottle’’ electron spectrometer

H. Handschuh, G. Ganteför, and W. Eberhardt

Rev. Sci. Instrum. 66, 3838 (1995); http://dx.doi.org/10.1063/1.1145446 (6 pages) | Cited 57 times

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The design of a high resolution ‘‘magnetic‐bottle’’‐type time‐of‐flight electron spectrometer suitable for the study of mass‐separated metal and semiconductor cluster anions is described. A high collection efficiency is achieved by using magnetic fields to guide the photoelectrons, so that vibrationally resolved photoelectron spectra can be recorded at a low laser pulse energy (<10 μJ focused to 1 mm2) avoiding multiphoton processes. Spectra of clusters with a very low relative abundance, for example the products of chemical reactions involving clusters, can be recorded and an energy resolution of 6 meV (48 cm−1) achieved. © 1995 American Institute of Physics.
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07.81.+a Electron and ion spectrometers
07.57.-c Infrared, submillimeter wave, microwave and radiowave instruments and equipment
07.60.-j Optical instruments and equipment

Electro‐optical modulators in particle detectors

T. Tsang and V. Radeka

Rev. Sci. Instrum. 66, 3844 (1995); http://dx.doi.org/10.1063/1.1145447 (11 pages) | Cited 1 time

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Results of an investigation to minimize the local electronics in particle detectors using electro‐optical intensity modulators are reported. The electrical charge signals from a particle detector are first applied to a low noise electronic charge‐sensitive preamplifier and the resulting signal charges are converted into optical signals using an integrated Ti:LiNbO3 Mach–Zehnder interferometric optical modulator. By driving the optical modulator with a low noise diode‐pumped Nd:YAG laser at a wavelength of 1.3 μm and detecting the output signals using a fast pulse shaping technique, the charge output of a particle detector can be measured at high rates with high accuracy up to 3 decades of dynamic range. The performance characteristics of such a detector signal transfer scheme, using first a single channel optical modulator and then a 16‐channel integrated optical modulator array, is reported. Using the charge output from a multiwire proportional chamber, this electrical charge to optical signal transfer scheme is compared to the conventional particle detection technique. Effects of radiation dose on the optical modulator are also presented. Finally, the implication of using such an optical technique is discussed. © 1995 American Institute of Physics.
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42.82.Gw Other integrated-optical elements and systems
29.40.-n Radiation detectors

Some observations of the effect of magnetic field and arc current on the vacuum arc ion charge state distribution

Frank J. Paoloni and Ian G. Brown

Rev. Sci. Instrum. 66, 3855 (1995); http://dx.doi.org/10.1063/1.1145448 (4 pages) | Cited 19 times

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The charge state distribution of ions produced in a vacuum arc plasma has been investigated for cathode materials Ti, Sn, and Pt as a function of arc current and magnetic field strength in which the arc is located. A vacuum arc ion source was used in combination with a time‐of‐flight charge state diagnostic. It was found that the arc impedance and the ion charge states increase substantially with magnetic field strength. While there was effectively no variation of charge state distribution with arc current for the case of zero applied field, there was a significant increase in the charge states with arc current when the applied magnetic field was 1 kG. © 1995 American Institute of Physics.
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52.80.Mg Arcs; sparks; lightning; atmospheric electricity
07.77.Ka Charged-particle beam sources and detectors
52.70.Nc Particle measurements

A merging preaccelerator for high current H− ion beams

T. Inoue, K. Miyamoto, M. Mizuno, Y. Okumura, Y. Ohara, G. D. Ackerman, C. F. Chan, W. S. Cooper, J. W. Kwan, and M. C. Vella

Rev. Sci. Instrum. 66, 3859 (1995); http://dx.doi.org/10.1063/1.1145449 (5 pages) | Cited 20 times

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The high power ion beams used in the next generation thermonuclear fusion reactors require high current negative ion beams accelerated to high energy, with high efficiency. One way to meet these requirements is to merge multiple low current density H− beamlets into a single high current beam. The feasibility of a high current merging preaccelerator was demonstrated in this experiment by merging 19 beamlets of H− ions distributed over a circular area 80 mm in diameter from a Japan Atomic Energy Research Institute negative ion source. H− ions were extracted at a current density exceeding 10 mA/cm2 at the ion source which operates at 0.13 Pa (1 mTorr), with a low arc power density (70 V×250 A). Spherically curved grids (with built‐in magnetic electron suppression) were used in the preaccelerator to focus the extracted beamlets into a single 104 mA, 100 keV beam. The merged beam has a diameter of 23 mm and a converging angle of ±30 mrad at the beam envelope. The rms emittance of the 104 mA merging beam was 1.00 π mrad cm, which is a condition acceptable to the electrostatic quadropole accelerator for further acceleration. © 1995 American Institute of Physics.
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28.52.Cx Fueling, heating and ignition
29.20.-c Accelerators

Acceleration of 100 mA of H− in a single channel electrostatic quadrupole accelerator

J. W. Kwan, G. D. Ackerman, C. F. Chan, W. S. Cooper, G. J. de Vries, W. F. Steele, M. E. Stuart, M. C. Vella, R. P. Wells, T. Inoue, Y. Okumura, and M. Mizuno

Rev. Sci. Instrum. 66, 3864 (1995); http://dx.doi.org/10.1063/1.1145450 (5 pages) | Cited 4 times

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Neutral beams for the next generation tokamaks will be based on multiampere negative ion beams with a beam energy of about 1.0 MeV and pulse lengths of a thousand seconds. High intensity dc beams at these levels of beam energy will require extensive development in electrostatic accelerators. At Lawrence Berkeley Laboratory, a two‐module electrostatic quadrupole (ESQ) accelerator was built to accelerate ions to 200 keV. In this experiment, up to 100 mA of H− beam current was obtained from a Japan Atomic Energy Research Institute cesiated volume source using a multiaperture preaccelerator which merged 19 beamlets into a single circular beam at the entrance to the ESQ accelerator. The H− beam was accelerated by the ESQ to accelerate 200 keV without any significant beam loss or emittance growth. © 1995 American Institute of Physics.
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28.52.Cx Fueling, heating and ignition
29.20.-c Accelerators

Effects of ambient gas in beam drift space on performance of high brightness and low energy ion beam

Takafumi Yoshikawa, Shin Nakamura, Yoshio Ueda, Masahiro Nishikawa, and Seiichi Goto

Rev. Sci. Instrum. 66, 3869 (1995); http://dx.doi.org/10.1063/1.1145451 (4 pages) | Cited 4 times

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Effects of the ambient gas in the ion drift space on the transport property of the low energy (155 eV) and high brightness beam are studied experimentally. A bucket ion source with single‐aperture triode extraction is used. Beam characteristics such as the divergence angle and the current density are improved by the increase in the ambient gas pressure in the high brightness beam (high deceleration voltage, −2000 V), but not in the low brightness beam (low deceleration voltage, −600 V). The beam spreading due to the space charge of the ion beam is seen at the low ambient gas pressure when the central current density, which is measured at 35 cm downstream side from the electrode system, exceeds 5 μA/cm2. The electron density in the ion‐beam plasma increases with the ambient gas pressure, but the space charge is not sufficiently neutralized by the electrons produced by the ambient gas atom ionization. © 1995 American Institute of Physics.  
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07.77.Ka Charged-particle beam sources and detectors
41.85.Ja Particle beam transport

Improved design of cusp‐type electron‐cyclotron resonance ion sources

S. Ishii and Y. Kato

Rev. Sci. Instrum. 66, 3873 (1995); http://dx.doi.org/10.1063/1.1145452 (3 pages) | Cited 1 time

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An ion source of electron‐cyclotron resonance using cusp magnetic field is designed. The field is generated with two cylindrical magnets polarized parallel to the axis of symmetry. Lines of magnetic induction are in this configuration longer than in conventional cusp machines. The plasma electrons escaping from a line cusp are repelled by applying negative potential to an electrode repeller. The repeller of low work function emits additional electrons. A whistler wave is launched through a helical antenna at a point cusp to produce overdense plasmas. An intense ion beam is formed by extracting ions at the other point cusp where the magnetic flux is focused. The repeller materials are sputtered at the line cusp and ionized in the plasma. The atomic flux from the cylindrical surface is focused at the center of plasma to give abundant ions from the solid materials. © 1995 American Institute of Physics.
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07.77.Ka Charged-particle beam sources and detectors
52.75.-d Plasma devices
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