bluuebunny/crossref_metadata_2025 huggingface dataset:
Automated polarimeter–macroscope for optical mapping of birefringence, azimuths, and transmission in large area wafers. Part II. Measurement setup and results
Authors: Bajor Andrzej L. , Kukla Marek J. , Pia̧tkowski Tadeusz , Sal/but Leszek , Spik Andrzej , Szwedowski Andrzej
Published: July 2002

In the first part of this work (see preceding paper) the theory of the method lying upon a novel concept of birefringence, azimuths, and transmission mapping in large area (up to 6 in. diameter) wafers has been presented. The arrangement consisting of two HR-type linear polarizers rotated simultaneously by a stepper motor versus an immobile wafer and using a video frame grabber (VFG)/TV camera detecting system is capable of collecting data and plotting the three maps within a fraction of a minute. A detailed error analysis presented in the preceding paper has shown that in usual circumstances the VFG with 256 grey levels enables determination of birefringence with an error not greater than approximately 5×10−7, whereas errors of the azimuths and transmission are fractions of a degree and of a percent, respectively. In this part of the work the arrangement constructed is fully described and a set of polariscopic images and measured maps are presented for an exemplary 4 in. GaAs wafer.
Super ESCA: First beamline operating at ELETTRA
Authors: Abrami A. , Barnaba M. , Battistello L. , Bianco A. , Brena B. , Cautero G. , Chen Q. H. , Cocco D. , Comelli G. , Contrino S. , DeBona F. , Di Fonzo S. , Fava C. , Finetti P. , Furlan P. , Galimberti A. , Gambitta A. , Giuressi D. , Godnig R. , Jark W. , Lizzit S. , Mazzolini F. , Melpignano P. , Olivi L. , Paolucci G. , Pugliese R. , Qian S. N. , Rosei R. , Sandrin G. , Savoia A. , Sergo R. , Sostero G. , Tommasini R. , Tudor M. , Vivoda D. , Wei F.-Q. , Zanini F.
Published: July 2002

The Super-ESCA beamline has been designed for high resolution core level spectroscopy of adsorbates on single crystal surfaces using soft x-ray synchrotron radiation. It receives the light from an 81 period undulator with 5.6 cm period and 4.5 m length in the storage ring ELETTRA. The tunability of this insertion device, at a storage ring electron energy of 2.0 GeV and the connected modified SX700 monochromator allows the performance of experiments at this beamline in the photon energy range 100–2000 eV. This beamline is now operational and first absorption spectra are presented which show available resolving powers varying from 8000 to 3000 for photon energies between 240 and 850 eV.
Performance of the neutron diagnostic system for Alcator C-Mod
Authors: Fiore C. L. , Boivin R. L.
Published: July 2002

Measurement of the global neutron production from the Alcator C-Mod tokamak has been done for all experimental operation in deuterium, which commenced in August 1993. Up to 3×1012 neutrons/s have been measured for diverse plasmas, including high current (1 MA), pellet injected, and rf heated discharges. Measurements during the initial run period were obtained using two sets of neutron detectors housed in polyethylene loaded moderator stations. Two more moderator stations containing additional neutron detectors have been obtained from LLNL and have been installed in the Alcator C-Mod experimental cell. The system has been calibrated using Cf252 placed at discrete points inside the Alcator C-Mod vacuum vessel. This paper presents a description of the diagnostic, followed by details of the calibration method and results. A discussion of the derivation of ion temperature from the global measurements is included with first results from the integrated system.
Fe i density measurements by laser induced fluorescence spectroscopy
Authors: Orsitto F. , Borra M. , Coppotelli F. , Gatti G.
Published: July 2002

The density of Fe atoms produced by bombardment of a stainless steel target by Ar+ ions was measured by laser induced fluorescence (LIF) using a tunable dye laser. The excitation transition involved was a 5D4→y 5D04 (λ=302.064 nm); measurements of the fluorescence signal, from the y 5D04→a 5F5 decay (λ=382.043 nm), were made by varying the laser power incident on Fe atoms by means of grey filters. An absolute calibration of the detection system allowed the determination of the number of the emitting atoms, versus the incident power. So the experimental curve of the fraction of total pumped atoms versus the saturation parameter was obtained. On the other hand, that fraction can be calculated by using standard rate equations for LIF process involving three level atoms. The result is strongly dependent on the model for the pumping laser pulse, particularly (as expected) at low incident power level. Assuming a realistic Gaussian temporal dependence for the radiation field energy flux at frequency v,  i.e., U (vt)  ∼  Uv0te−t2 and calculating the fraction of atoms pumped by the incident pulse, an agreement better than assuming a square time dependence for U(v,t) was found. The measurement sensitivity limit is 109 atoms/cm3 when LIF diagnostic on FTU is considered including plasma emission background.
Absolute calibration of a vacuum Czerny–Turner spectrometer in the range 1200–7000 Å
Authors: Carraro L. , Cortiana M. , Puiatti M. E. , Sattin F. , Scarin P. , Valisa M.
Published: July 2002

The vacuum Czerny–Turner high-resolution spectrometer observing the plasma of the reversed-field-pinch device RFX has been absolutely calibrated in the spectral range 1215–7000 Å, in order to measure the emission spectrum in absolute units, with particular reference to the heliumlike carbon and oxygen ion lines. The source used to calibrate the spectrometer in the vacuum and near-ultraviolet region is a deuterium lamp; its spectral radiance was determined by comparison with the synchrotron radiation of the electron storage ring BESSY, in Berlin. A typical error of 35% has been estimated. In the visible a standard tungsten lamp has been used. The calibration has been transferred to an ultragrazing incidence XUV spectrometer by means of the branching-ratio technique, using the intensity ratio between the intercombination 1s2 1S–1s2p 3P0 and the 1s2s 3S–1s2p 3P0 transitions of carbon, nitrogen, and oxygen heliumlike ions.
Saturation recovery in electron spin resonance with pulsed observing microwave power
Authors: Braganza O’Neil P. , Das Ranjan , Prabhananda B. S.
Published: July 2002

By appropriate instrumentation, saturation recovery in electron spin resonance has been observed with pulsed observing microwave power. The observing power was ∼100% amplitude modulated with a low duty cycle, in order to sample the magnetization periodically during its recovery from saturation. This technique has the following advantages in the saturation recovery studies of systems having long spin-lattice relaxation times T1: (i) Advantages associated with capacitor-coupled amplifiers are retained. (ii) Higher relaxation amplitudes could be obtained and at the same time the deviation of the observed relaxation time from true spin-lattice relaxation time T1 could be reduced. In the conventional saturation recovery experiments, higher relaxation amplitudes needed to achieve better signal-to-noise ratio require high observing microwave power, which, however, makes the observed relaxation time smaller than T1. The performance and efficacy of this technique have been evaluated using 2,5 di-tert-butyl 1,4 benzosemiquinone anion in n-butanol.
Efficient negative-ion sources for tandem injection (invited)
Authors: Diamond W. T. , Imahori Y. , McKay J. W. , Wills J. S. C. , Schmeing H.
Published: July 2002

Tandem-accelerator operation requires a source of negative ions. The earliest negative-ion sources were based on charge exchange of positive ions from a rf or duoplasmatron source. The development of the sputter-ion source in the 1970’s produced a revolutionary change in the number of negative-ion beams for Tandem operation. This article will review operational characteristics of sputter-ion sources coupled to large Tandem accelerators. These characteristics and matching of the ion source to the accelerator are determining factors for the production of useful beam intensities for physics experiments. A new approach using a 2.45 GHz microwave ion source to produce a high-quality, positive-ion beam coupled to a charge-exchange canal is being developed at Chalk River Laboratories, and some results of this development program will be presented. Plans for future development include the investigation of direct extraction of negative ions from a microwave-driven plasma.
Can piezoelectric accelerometers be used to actively damp the mechanical suspensions in laser interferometric gravitational wave detectors
Authors: Veitch P. J. , Hough J. , Morrison E. , Robertson D. I.
Published: July 2002

An investigation of the use of mass-loaded piezoelectric accelerometers for active damping of high Q, mechanical, vibration isolation suspensions is reported. The transfer function and noise of the accelerometer are modeled, and the predicted noise compared with measurements. A servo which damps the normal modes of a two-stage suspension by sensing the acceleration of, and feeding back to, the intermediate mass is then modeled. The rms and ‘‘high frequency’’ closed loop motions of the isolated mass are calculated.
Duoplasmatron ion source for proton and deuteron intense beams at low energy (abstract)
Authors: Marinescu L. , Dima R. , Dobrescu S.
Published: July 2002

The duoplasmatron source was specially designed as a component of the hydrogen and deuterium negative polarized ion source, of Lamb–Shift type, for equipping the FN–Tandem Accelerator in Bucharest. The source can operate long-term at an arc power of 2.5 kW with an intensity of the arc current of 10–11 A. The duoplasmatron source anode is of a special construction in order to allow a strong cooling and a quick adaptation of some cups for the plasma expansion. Three variants of the extraction ion-optics configuration have been analyzed by computer and then experimentally carried out and tested. All the extraction ion-optics configurations employ plasma expansion cups and the process of deacceleration of the beam down to energies of 500–1000 eV is taking place inside of a magnetic lens. The proton and deuterium beam intensity obtained beyond the magnetic lens may exceed 10 mA, function of the discharge conditions in the arc and the ion-optics configuration employed. The ion composition of the beam (H1, H2, H3) function of the discharge parameters in the arc, has also been analyzed and the results showed that the percentage of the atomic ions is higher than 70%.
The polarized ion source for COSY
Authors: Weidmann R. , Glombik A. , Meyer H. , Kretschmer W. , Altmeier M. , Eversheim P. D. , Felden O. , Gebel R. , Glende M. , Eggert M. , Lemaitre S. , Reckenfelderbäumer R. , Paetz gen. Schieck H.
Published: July 2002

The polarized ion source for COSY-Jülich has been set in operation. The source produces H− or D− ion beams by means of a charge exchange reaction. For the first time beam acceleration in the injector cyclotron and a first measurement of the beam polarization downstream of the cyclotron took place. The working scheme of this colliding-beam source and the latest results are discussed.
Spectroscopic studies in the VUV range in electron cyclotron resonance ion sources
Authors: Jettkant B. , Berreby R. , Hitz D. , Druetta M.
Published: July 2002

Using a calibrated 3 m grazing incidence spectrometer-type Romand Vodar equipped with channel plates detector, we studied emission lines in the range between 10 and 100 nm of ions from plasma generated in two different electron cyclotron resonance ion sources (the new CAPRICE and QUADRUMAFIOS). In the VUV range, one can observe many emission lines from nearly all ionization states. From the measurements, performed on oxygen and helium mixture plasmas and thanks to a theoretical model, an estimation is done giving the electronic and ionic densities for different rf powers.
An emittance–mass scanner for small-mass, low-energy beams
Authors: Yuan D. , Jayamanna K. , Kuo T. , McDonald M. , Schmor P.
Published: July 2002

An on-line emittance–mass scanner (EMS), with a size of 10 cm×10 cm×8 cm, has been developed for use with low energy and light ion beams (A<40) at TRIUMF. Computerized data acquisition and procession give the rms emittances, intensities, and contour plots of each beam component. The angular resolution of the scanner is ±1.0 mrad, the maximum divergence of each component that the scanner can take is 140 mrad. Some experimental results of the measurement are given. The comparison between the contour shapes and the values of the emittance measured by both the emittance scanner and EMS is in good agreement.
Radio frequency multicusp ion source development (invited)
Authors: Leung K. N.
Published: July 2002

The radio-frequency (rf) driven multicusp source was originally developed for use in the Superconducting Super Collider injector. It has been demonstrated that the source can meet the H− beam current and emittance requirements for this application. By employing a porcelain-coated antenna, a clean plasma discharge with very long-life operation can be achieved. Today, the rf source is used to generate both positive and negative hydrogen ion beams and has been tested in various particle accelerator laboratories throughout the world. Applications of this ion source have been extended to other fields such as ion beam lithography, oil-well logging, ion implantation, accelerator mass spectrometry and medical therapy machines. This paper summarizes the latest rf ion source technology and development at the Lawrence Berkeley National Laboratory.
On the development of a 15 mA direct current H− multicusp source
Authors: Kuo T. , Yuan D. , Jayamanna K. , McDonald M. , Baartman R. , Schmor P. , Dutto G.
Published: July 2002

A 15 mA dc H− multicusp source has been developed for injection into a TR30 cyclotron. This source is also used with a 900 kV tandem accelerator to obtain 10 mA protons at 1.8 MeV. The program is an extension of the 5–7 mA dc H− cusp source developed at TRIUMF during 1989–1990. Major efforts include the search for the optimal filament materials, shape, and location; comparison of cusp line confinement and magnetic filtering of electrons at the extraction region; optimization of extraction lense configuration; and upgrading of vacuum and power systems capability. The source is noncesiated and the maximum arc power available is only 5 kW. After the H− beams pass through an electron suppression grid and a 20 mm collimator, we obtained 15 mA with 0.66 π mm mrad 4 rms normalized emittance. At this output the e/H ratio was about 4. The best normalized emittance occurs around 5–7 mA, having a value of 0.37 π mm mrad. Further development in the near future is planned using cesium and multiple apertures in the hope of increasing dc H− currents to 30 mA while holding the normalized emittance below 0.75 π mm mrad.
Study of the electron resonance and the development line in both ECRISs and RFISs (abstract)
Authors: Zakhary S. G.
Published: July 2002

The motion of a charged particle in a crossed rf field and dc magnetic field describes the occurrence of resonance (increase of the energy gained by the particle between collisions) which causes low breakdown voltage, higher plasma intensity, and higher extracted ion current. The resonance in the microwave discharge is essential for plasma electron heating. The development line in both ECRIS’s and RFIS’s includes an increase of the electron population in the discharge to intensify the plasma and increase the extracted ion current; plasma cooling with the use of electron injection or gas mixing increases the lifetime of the ions in the plasma allowing for multiple ionization collision and increase of the highly charged ion species. Adaptation of both electrical and geometrical properties of these sources can lead to obtaining lower beam emittance.
Light ion heating in electron cyclotron resonance ion sources
Authors: Meyer D. , Nadzeyka A. , Remscheid A. , Wiesemann K.
Published: July 2002

The experiments described here were performed at a 5 GHz electron-cyclotron-resonance ion source with a magnetic hexapole. The discharge was run in argon. By launching a fast magnetoacoustic wave from the high-field side (end on) we heated hydrogen ions—present in traces from the residual gas—at their fundamental ion cyclotron resonance (ICR) frequency of 2.2 MHz with 5 W only. As a consequence the currents of Arq+ ions extracted from the source were significantly increased for q≥5 while the currents of lower charged argon ions were decreased, indicating an enhanced plasma confinement. However, a reduction of the hydrogen content in the residual gas resulted in a reversal of the effect of ICR heating.
Experimental investigation of the afterglow of the pulsed electron cyclotron resonance discharge
Authors: Langbein K.
Published: July 2002

During the afterglow of the pulsed electron cyclotron resonance discharge, currents can be extracted, which are substantially higher than the ion current during the heating phase of the plasma. This is especially the case for the high charge states of heavy ions. An operating regime was found, which gives an extremely stable and reproducible afterglow. The variation from pulse to pulse is hardly visible and the long-term stability is also very good. This mode, which made the setting up and operation of the accelerators much easier than is normally the case, can also give an insight into the processes responsible for the afterglow. An investigation of the shape and duration of the afterglow for the different charge states of lead is presented. A 1/ζ2 dependence for the decay time of the afterglow was found for operation with oxygen, while no such dependence appears for operation with neon as the auxiliary gas.
Acceleration of high-current ion beams
Authors: Spädtke P. , Emig H. , Klabunde J. , Mayr R. , Rück D. M. , Tinschert K.
Published: July 2002

At GSI typical currents for injection into the Wideröe are in the range of μA to 1 mA, depending on the specific ion. After upgrading the UNILAC with a high-current injector (Beam Intensity Upgrade of the GSI Accelerator Facility, A Technical Status Report, GSI Report GSI-95-05, June 1995), these currents will be in the range of up to several mA. For the design ion (U4+) up to 15 mA are desired to reach the space charge limit of the planned RFQ. The input energy of the RFQ is 2.5 keV/u requiring a dc voltage of about 150 kV. This voltage will be distributed to the extraction (30–50 kV) and to the dc acceleration column (about 100 kV).
First operation of HiECR-3 ion source for 14–18 GHz
Authors: Hattori T. , Katayose T. , Yamada S. , Kitagawa K. , Sekiguchi M. , Yamashita Y.
Published: July 2002

The new HiECR-3 ion source has been designed to have a mirror field and a hexapole field strong enough for both 14 and 18 GHz operation. We designed, manufactured, and operated the HiECR-3, for studying characteristics of volume and surface dependence on the electron cyclotron resonance (ECR) plasma zone. From these measurements of the ECR plasma, we examined many problems. They are the ECR plasma zone, the extraction efficiency from the plasma zone, electron injection from another ECR plasma zone, and volume and surface of the ECR plasma zone.
Generation of energetic barium atomic beam for fusion plasma diagnostics
Authors: Murakami K. , Fukuura Y. , Mima H. , Katsumata I.
Published: July 2002

A Ba+ beam is generated in a thermal contact–ionization plasma source made of a rhenium-foil cylinder 5 mm in diameter inserted into a tungsten cylinder for protection. The source can be heated up to about 3000 K. The maximum current of Ba+ already attained is 200 μA. The beam can be accelerated to 40 keV. The Ba+ beam is passed through a Li-vapor cell and neutralized by a charge-exchange reaction with Li atoms. A 100 μA/e Ba beam has already been obtained. The next subject is to measure the increase of energy spread of the beam passing through the Li cell by collisions with vapor atoms. An optical system has been developed for measuring it by the Doppler broadening of spectral lines emitted by Ba and Ba+ beam particles. Results of optical measurement are presented. The production of slow energy components has been observed. They are attributable to the head-on collision of Ba beam particles with a Na atom and with a K atom as impurities in the Li vapor cell. Because of the head-on collision, the energy spread of the main Ba beam is not changed in passing through the cell.
Hollow cathode magnetron ion source with axial extraction
Authors: Miljević Vujo I.
Published: July 2002

Magnetron ion source with a hollow mesh cathode and an axial extraction have been studied. Ion current up to 1 mA, when operating gas is hydrogen, has been obtained with a 0.5 mm diam. exit aperture and an extraction voltage up to 10 kV.
Radio frequency beam chopping in a surface-plasma-type negative-ion source
Authors: Shinto K. , Takagi A. , Kinsho M. , Ikegami K. , Igarashi Z. , Machida S. , Yoshii M. , Mori Y.
Published: July 2002

A direct fast-chopped beam extracted from a surface-plasma H− ion source is proposed and a preliminary test has been examined. The converter bias voltage is modulated by rf pulses and the extracted H− beam is observed. The direct fast-chopped H− beam extracted from the ion source has a good response to the modulation of the converter bias voltage, as expected. The chopped H− beam extracted by this method has been injected into the 500 MeV booster synchrotron at KEK-PS.
Modeling of gas flow in the simulation of H− ion source
Authors: Ogasawara Masatada , Okuda Yasuhiro , Shirai Mikito , Mitsuhashi Seiji , Hatayama Akiyoshi
Published: July 2002

Actual gas supply into the ion source is modeled. Filling pressure is related to gas flow rate and conductance of the H− extraction system. The rate equation for the H2 molecule with gas inflow and outflow rates related with the filling pressure are employed in the numerical simulation of a negative hydrogen ion source. With the results of numerical simulation, the H number conservation relation and pressure balance equation are shown to be inaccurate especially for higher electron temperature. Actually for 5 eV of electron temperature, lost H2 density amounts to 79% and the pressure becomes 5 times the original pressure of 5 mTorr. Even for a low pressure of 3 mTorr, the lost fraction is 67% for 5 eV of the electron temperature. This inaccuracy is large in high power and even for low pressure operation of the ion source.
Acceleration of light ions from a laser source in a four vane radio frequency quadrupole
Authors: Collier J. , Haseroth H. , Kuttenberger A. , Langbein K.
Published: July 2002

Laser ion sources have a great potential for the production of large numbers of highly charged heavy ions as required for fixed target experiments at the SPS and for the future LHC. However, the beam from a laser ion source (LIS) has certain characteristics, like the short pulse duration, the high total current, the large energy spread and the time varying beam divergence, which make its acceleration in the subsequent linear accelerators difficult. As the first accelerator for the injector chain will be a radio frequency quadrupole (RFQ), a proof of principle of acceleration of ions from the laser ion source was performed, using a 200 MHz four-vane RFQ. This structure, which was originally designed for the preacceleration of light ions for CERN’s LINAC I, requires an injection energy of 5.6 keV/u and is therefore not well suited for ion beams from a LIS. In spite of this drawback, ion currents approaching the space-charge limit of the RFQ (i.e., several mA of Al9+–Al11+), could be accelerated. The results of these experiments and the special problems of the application of the LIS will be presented.
Negative hydrogen ion production in multicusp volume source with a pulsed discharge (abstract)a)
Authors: Bacal M. , Belchenko Yu. I.
Published: July 2002

The pulsed operation of a negative ion volume source has been investigated, both with a magnetic filter present and without it, under conditions of full-scale acceleration of the extracted negative hydrogen ion beam. We report the observation of three afterglow negative ion peaks. As the negative ion current during the discharge pulse, each of the afterglow peaks can be optimized by varying the pressure, the plasma electrode bias and the extraction voltage. Under optimum conditions, the negative ion current during the discharge pulse exceeds the afterglow peaks.
Praseodymium alloy ion source for focused ion beam implantation in superconductors
Authors: Machalett F. , Seidel P. , Mühle R.
Published: July 2002

We have investigated the emission characteristics of a liquid alloy ion source for focused ion beam implantation of praseodymium (Pr) ions in high-Tc superconductors. The element Pr was used in a ternary Au–Si–Pr alloy with a low melting point and a low vapour pressure. The melting properties of the alloy were determined by differential thermal analysis. We have measured the emission current stability, the current–voltage characteristics and the mass spectra using a single magnetic mass spectrometer. The ion source exhibits a good performance even after storage for several months in air. The mass spectra show a high intensity of double charged Pr ions.
A diamond-anvil cell for single-crystal x-ray diffraction studies to pressures in excess of 10 GPa
Authors: Allan D. R. , Miletich R. , Angel R. J.
Published: July 2002

A new diamond-anvil cell for single-crystal x-ray diffraction structural studies is presented. By including a simple mechanism for adjusting the parallelism of the opposing diamond culets, the stability of the gasket is maintained to higher pressures than was achieved in earlier cells of a similar two-platen design. Equipped with 600 μm culet diamond anvils, the cell has been tested to a pressure of 25 GPa and has been used successfully for equation-of-state measurements and crystal structure determinations to 10 GPa.
Fourier transform spectroscopy applied to photoluminescence: Advantages and warnings
Authors: Bignazzi A. , Grilli E. , Radice M. , Guzzi M. , Castiglioni E.
Published: July 2002

A Fourier transform (FT) apparatus specially dedicated to photoluminescence measurements in the near infrared has been assembled. The details of the experimental setup and a comparison with a conventional dispersive apparatus are discussed. Advantages of the FT approach for photoluminescence measurements as well as warnings about limitations and artifacts are illustrated.
Photoacoustic cell for dynamic measurements with nanosecond time resolution
Authors: Puchenkov Oleg V. , Malkin Shmuel
Published: July 2002

A design of a photoacoustic (PA) cell for dynamic measurements in liquid samples with nanosecond time resolution is presented. The design is based on a layered scheme of laser-induced sound excitation and detection. A theoretical basis for the use of the cell in dynamic PA diagnostics and in pulsed acoustic spectroscopy is given. The cell parameters which determine its performance in both applications are established, and ways of cell optimization are discussed. The validity of the theoretical description was proven in a set of calibration experiments. The functioning of the cell as a PA-diagnostics device was tested on a model photochemical system (the quenching of the triplet state of benzophenone by 2,5-dimethyl-2,4-hexadiene). With a slight modification the cell was used for pulsed broadband acoustic spectroscopy to probe the structural relaxation in formic acid in the frequency range of 2–20 MHz.
Ion sources for space thrusters (invited)
Authors: Grigoryan V. G.
Published: July 2002

One of the main tasks of the creation of spacecraft power plants is raising the thrust producing jet velocity. Conventional chemical engines create jet velocities in the range of 3000–4500 m/s. This situation can be drastically changed if beams of charged particles accelerated by electric and magnetic fields are used to produce thrust. In such cases practically any jet velocity might be created, which considerably enlarges the number of tasks being fulfilled by spacecraft having such types of thruster. Several types of electric propulsion thrusters exist nowadays. They differ in the principles of acceleration of charged particles, for example, arc jets, magnetic plasma dynamic thrusters, stationary plasma thrusters, pulse thrusters, and ion thrusters. Electric propulsion thrusters are practically the accelerators of charged particles which operate under rather strict requirements concerning energy consumption and lifetime. Since the mid-fifties in Russia there have been intensive studies of practically all types of electric propulsion thrusters, including their tests in space, and beginning with the mid-seventies they have been practically used aboard spacecraft with a long, active lifetime. The study of the physical process involved together with the research design allowed Russian scientists to develop electric propulsion thrusters in the power range from hundreds of watts to tens of kilowatts, with jet velocities between 20000 and 50000 m/s and lifetime more than several thousand hours.
Volume source of hydrogen negative ions based on reflexive discharge: Theory and experiment (abstract)a)
Authors: Goretsky V. P. , Ryabtsev A. V. , Soloshenko I. A. , Tarasenko A. F. , Schedrin A. I.
Published: July 2002

The results of theoretical and experimental studies of the stationary volume source of hydrogen negative ions based on reflexive discharge are presented. Measurements of plasma parameters and emission characteristics are accomplished, and the optimization of ion source geometry is provided. The best parameters of the ion beam extracted from the source across the magnetic field are as follows: current 40 mA, current density—80 mA/cm2, emittance along the magnetic field—3×10−5 cm rad, emittance across a magnetic field—1×10−5 cm rad. The calculation of basic beam properties is performed by numerical solution of the Boltzmann equation for electrons, balance equations for more than 300 elementary processes in gas discharge plasma, and equations of ion and electron motion. The calculated dependencies of hydrogen negative ions’ current density in the plane of emission slit on the gas pressure and the discharge current are found to be in a good agreement with the experimental data.
Optical thickness profiling using a semiconductor laser confocal microscope
Authors: Saloma Caesar , Matsuoka Katsunori , Kawata Satoshi
Published: July 2002

A semiconductor laser confocal microscope is developed for measuring the optical thickness of thin transparent samples at high spatial resolution. The optical sectioning capability of a confocal microscope, and the sensitivity of the laser output to optical feedback, are both utilized to detect the presence of a nonabsorbing sample in the path of the probe beam that is initially focused onto a plane mirror. The index mismatch at the sample interface defocuses the beam away from the mirror and reduces the amount of optical feedback. The optical thickness is computed from the amount of axial displacement that the mirror must be given to regain maximum feedback. The laser power output is monitored using the monitor photodiode in the laser package. When the geometrical thickness of the sample is known a priori, the technique can be used to measure its refractive index and vice versa. The smallest and largest measurable sample thickness are determined by the sharpness of the axial intensity response of the microscope and the working distance of the focusing objective, respectively. Distortions in the central spot distributions of the response degrade the precision of the measurement technique. We demonstrate the technique for both the 830 and 780 nm laser output wavelengths, by classifying cover glasses of differing optical thickness (geometrical thickness range: 70–536 μm, refractive index=1.523), as well as to image the sudden index changes found in the phase ridge formed by two closely spaced cover glasses (surface flatness=7 μm) of different geometrical thickness. Our experiments show that at least for objectives with small numerical apertures (≤0.25), spherical aberrations are negligible and our measurements are to within the accuracy set by the glass manufacturer.
Fourier transform infrared cell for surface studies at controlled temperatures and in controlled atmospheres with time resolution and spatial resolution
Authors: Self V. A. , Sermon P. A.
Published: July 2002

A new micro-Fourier transform infrared cell has been constructed and evaluated using (i) the transformation of aurichalcite crystals at 298–475 K, (ii) the adsorption/desorption of pyridine on a Cu2O/ZnO junction, and (iii) the adsorption of CO on Pt/alumina pellets; it enables spatial and time resolution of processes in such diverse samples held at known thermal and baric conditions. The potential of this cell in catalytic and analytical science is considered.
High velocity ion microprobes and their source requirements (invited) (abstract>
Authors: Legge G. J. F. , Moloney G. R. , Colman R. A. , Allan G. L.
Published: July 2002

For many years, beams of high velocity ions have been widely used for relatively nondestructive investigation of surfaces or thin films. Many properties may be investigated, associated with the large number of interactions, most of the information obtained being complementary to that from high velocity electron beams or low velocity ion beams. Recently there has been increasing interest in the application of microbeams of these high velocity ions and two streams of activity have emerged—one using traditional techniques and requiring beams of hundreds of picoamps to give spatial resolutions of the order of 1 μm, the other using many new techniques and requiring currents from femtoamps down to single ions to give resolutions of an order of magnitude better. In both cases, the resolution is limited by the low brightness of ion sources commonly used in high energy ion accelerators. These energies commonly are of the order of 3 MeV for very light ions, but there are several developing fields in which much higher energies and heavier ions are of interest. This paper looks at the wide range of information obtainable with these high velocity ion microprobes, the limitations placed on them by their ion optics, the great improvements which would flow in all cases from the development of better ion sources, the best candidates for such sources, and some recent progress.
Initial results of the 2.45 GHz excitation of the superconducting ECR ion source in its high-B mode (abstract)a)
Authors: Srivastava A. K. , Antaya T. A.
Published: July 2002

The ‘‘frequency squared scaling’’ law, relied upon to enhance the production of high charge state ions from electron cyclotron resonance (ECR) ion sources, indicates that low frequencies of operation may not be viable for production of high ion densities, and hence for the production of high charge state ions. The superconducting electron cyclotron resonance ion source (SCECR) at the National Superconducting Cyclotron Laboratory is a fully superconducting, hexapole stabilized tandem mirror ECR ion source with a multimode microwave cavity. When operated at its optimized high magnetic field (high-B) mode at 6.4 GHz, the high charge state current output of the SCECR approaches all existing ECR ion sources, including higher frequency ECR ion sources (ECRIS). In this study, the SCECR is operated at 2.45 GHz in its high-B mode that is scaled down for that frequency of operation. Initial results with oxygen and argon ion production at 2.45 GHz are presented. It is demonstrated that the SCECR can produce a plasma from which multiply charged ions of up to O7+ and Ar13+ can be extracted with ion current intensities comparable to several higher frequency ECRIS. This study concludes that 2.45 GHz is indeed a viable frequency for production of moderate intensities of multiply charged ions. This may lead to a simpler, and more cost effective microwave apparatus, with a less demanding magnetic field configuration.
A simple electron cyclotron resonance ion source (abstract)a)
Authors: Welton R. F. , Moran T. F. , Feeney R. K. , Thomas E. W.
Published: July 2002

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.
Fifty centimeter ion beam source (abstract)a)
Authors: Hayes A. V. , Kanarov V. , Vidinsky B.
Published: July 2002

A 50-cm-diam ion source and its industrial applications are described. This is the largest commercial ion source presently available for ion beam etching and deposition over a full 20 in. diam. It has been used to generate beams of argon ions at 300–900 eV of ion energy and beam currents of 1–5 A with standard filament-type cathodes. Operation at even higher current levels is possible with high emissivity hollow cathodes. A presentation of general performance characteristics of the ion source is given and some of the special considerations required for reliable and cost-effective operation of large scale ion beam systems are discussed. To illustrate the application of this source, a brief description of a fully automatic production ion beam etching system developed around this ion source is given along with a description of the etch results. This system can simultaneously etch a batch of five 6-in.-diam wafers with etch rates of nickel–iron exceeding 500 A/min. The etch uniformity is excellent.
Plasma production via laser-induced photoemission (abstract)
Authors: Pickard D. S. , Kunkel W. B. , Leung K. N. , Young A. T.
Published: July 2002

The feasibility of laser-induced photoemission as a driving mechanism for short plasma pulse production is currently being investigated with a pulsed excimer laser at 248 nm. Low work function materials such as LaB6 and barium are used as cathode materials and the resulting plasma characteristics are being examined. Results from early measurements of the barium photocathode show a strong dependence of the photoemitted current on the source pressure and cathode voltage. Additionally, the temporal behavior of the emitted electron pulse is found to consist of two components: a short 50 ns burst corresponding to laser-induced photoemission, and a larger, longer 100 ns pulse increasing from the tail end of the photoemitted electron pulse.
Photoacoustic mapping of the amplification region and characterization of a dye laser amplifier
Authors: Ramos-Ortiz G. , Villagrán-Muniz M.
Published: July 2002

Mapping of the amplification region and full characterization of a dye laser amplifier by means of a photoacoustic technique are presented. The acoustic signals generated in the pumped medium as a consequence of nonradiative transitions are gain dependent. We use the ratio between the acoustic signal measured when the oscillator beam passes through the amplifier, to the acoustic signal when it is blocked, as a figure of merit of an amplifier stage. By using the oscillator beam as a spatial probe of the amplifier gain region, it is possible to map the optically inverted medium, assigning a photoacoustic ratio to each point of the medium.
High temperature coefficient of resistance in vanadium oxide diodes
Authors: Kuznetsov V. A. , Haneman D.
Published: July 2002

Evidence regarding the high temperature coefficient of resistance (35% per °C) in vanadium oxide multiple thin film diodes has been obtained, indicating that the source is a vanadium oxide substance formed between multiple layers of deposited vanadium. Effects of top contacts are detailed. The devices also show high sensitivity to mechanical pressure.
Polarization of x-ray Li- and Be-like Fe satellite lines excited by an electron beam
Authors: Shlyaptseva A. S. , Mancini R. C. , Neill P. , Beiersdorfer P.
Published: July 2002

We have calculated the polarization properties of dielectronic satellite lines in Li- and Be-like Fe ions excited through resonance electron capture by a monoenergetic electron beam. Following the density matrix formalism, we have computed the degree of polarization and the spectral intensity distribution of dielectronic satellites associated with a given polarization state. Theoretical results were compared with experiments performed at the Livermore Electron Beam Ion Trap where satellite line emission from Fe ions was simultaneously recorded with two crystal spectrometers. These results are relevant to diagnostic applications of x-ray line polarization spectroscopy in plasmas.
Micrometer-sized nozzles and skimmers for the production of supersonic He atom beams
Authors: Braun J. , Day P. K. , Toennies J. P. , Witte G. , Neher E.
Published: July 2002

Micrometer-sized nozzles and skimmers made from drawn glass tubes are described and tested for the production of highly monoenergetic He atom beams. Glass nozzles with diameters between 1 μm and 4 μm when operated at He source stagnation pressures of up to 1000 atm provide intense beams with measured speed ratios of S=50–100, in good agreement with the predicted behavior scaled from nozzles with larger openings. Miniature glass skimmers with diameters as small as 3 μm were also successfully tested with conventional 10 μm diameter nozzles. These miniature nozzle-beam sources can be used to greatly reduce the size of present-day He-atom surface-scattering time-of-flight spectrometers and to reduce the number of vacuum stages and the size of vacuum pumps. They also open up new experimental possibilities as illustrated by measurements of the spatial profiles of seeded nozzle beams.
A 3–350 K fast automatic small sample calorimeter
Authors: Pecharsky V. K. , Moorman J. O. , Gschneidner K. A.
Published: July 2002

A description of a fully automated calorimeter for rapid measuring the heat capacity of solids in the temperature region from ∼3 to ∼350 K and in magnetic fields from 0 to 10 T is given. A comprehensive mathematical analysis of the semiadiabatic heat pulse technique for heat capacity measurements on solid materials resulted in the development of the necessary formal algorithms for the complete automatization of the data collection process. Simultaneously a procedure for the on-line evaluation of uncertainties in the measured heat capacity data is developed. An approach which eliminates the need for a separate temperature sensor(s) attached to an adiabatic heat shield(s) used to maintain semiadiabatic conditions during heat pulse heat capacity measurements has been proposed and tested. The sensorless technique provides reliable control of the heat transfer inside a vacuum chamber and results in accurate heat capacity data. The calibration results show that the heat capacity can be measured with an average accuracy better than 1% on small samples (∼1 g) over the whole temperature region.
General purpose high-performance electron cyclotron resonance ion source for production of multicharged ions
Authors: Sortais P. , Bex L. , Maunoury L. , Lamy T. , Villari A. C. C.
Published: July 2002

There is a growing interest for high performance electron cyclotron resonance ion source (ECRIS) working in various environments and dedicated to various purposes. In this article we will present three typical machines using classical FeNdB radial magnets and coils. The first one, called “SuperNanogan II,” is a fully permanent magnet machine, copying exactly the ECR4 magnetic structure. Here the purpose consists in producing high currents of high charge state ions on a high voltage platform (up to 250 μAe of Ar10+40 and Ca11+48). The second one, called “Super n+,” is a very high magnetic field machine dedicated to be used as high performance charge booster for the 1+/n+ ISN/GANIL program. The source is built around a ∅ 9 cm minimum |B| structure closing a maximum closed magnetic line of 1.8 T, so allowing functioning points from 2.45 to 35 GHz. The third one is a hybrid machine using an existing 4 T superconducting mirror field, where it is possible to place inside a well optimized 1.6 T FeNdB multipole. This machine can be used as a classical 6.4 to 35 GHz ECR ion source or just as an “ECR ion trap” in order to optimize the trapping of hydrogenlike ion for spectroscopic purpose.
Propagation of metal vapor vacuum arc ions into electron cyclotron resonance ion sources
Authors: Cavenago M. , Kulevoy T. , Vassiliev A.
Published: July 2002

A metal vapor vacuum arc (Mevva) ion source was finally installed and operated inside the electron cyclotron resonance (ECR) ion source Alice; Mevva cathode was made of Al, while ECR buffer gas was nitrogen, and among residuals, argon. Installation, hardware control, and improvements of diagnostic are discussed. Magnetic analysis of the ECR emitted current shows the presence of an Al3+ peak of about 5–10 μA following Mevva pulse end after 15 μs, against a steady state current of 10 nA. Peak width is about 5 μs, which is the limit of our current amplifier. Peak remains when ECR is turned off. Application of a bias potential of ±46 V to the Mevva anode shows fairly small effects on time of flight, which may indicate a large kinetic energy of Mevva ions (280 eV) at the end of Mevva shot. Bias voltage and ECR operation proved compatible only at low power, in present installation; then, some or most of Mevva ions are not trapped inside the ECR.
Measurement of plasma density using wavelet analysis of microwave reflectometer signal
Authors: Bruskin L. G. , Mase A. , Tokuzawa T. , Oyama N. , Itakura A. , Tamano T.
Published: July 2002

A new method of plasma density profile reconstruction in microwave reflectometry is proposed and implemented on an X-mode broadband reflectometer of the GAMMA 10 mirror device with an ultrafast sweep rate of 10–20 μs. The proposed method makes use of the wavelet transform of the detected signal. Excellent resolution in the time-frequency domain, inherent to wavelet analysis, allows one to obtain a radial electron density profile for every frequency sweep. The electron density reconstruction algorithm, besides the wavelet transform of the reflectometer signal, also includes the calibration, profile initialization, and the solution of an integral equation, ultimately yielding the local values of the electron density. Calibration of the measured signal phase and profile initialization is performed using the independent results of microwave interferometry. Inversion of the integral equation is implemented utilizing the gradient method, numerically stable even for plasma regions with steep density gradients and density profile plateaus. A wavelet-based profile reconstruction algorithm is especially advantageous for monitoring transient plasma phenomena and fast processes, such as in pellet injection, ultrafast swept reflectometry, and short pulsed reflectometry.
Conceptual design of a helicon ion source for high-current dc accelerators
Authors: Hwang Y. S. , Hong I. S. , Eom G. S.
Published: July 2002

Characteristics of helicon plasmas are examined as a candidate for accelerator ion sources. Helicon plasmas have much higher density with very high power efficiency in a relatively lower magnetic field than electron cyclotron resonance plasmas do. High electron density and high electron temperature are beneficial to extract high ion current density. Low magnetic field favors for low-emittance accelerators. Taking advantage of placing antenna outside of the plasma chamber, source contamination can be kept low enough to maintain a stable operation for longer periods. Based on these characteristics, new designs of high current ion sources using helicon waves are proposed for accelerator applications for the first time.