bluuebunny/crossref_metadata_2025 huggingface dataset:
Optimization of a two-stages electrostatic reflex ion source
Authors: Farchi A. , Wartski L. , Boukari F. , Roy V. , Coste Ph. , Aubert J.
Published: July 2002

In our argon, oxygen, or nitrogen broad beam ion source, 80 mm in diameter, which is either an electrostatic reflex ion source, or a magnetic and electrostatic reflex ion source, the hot filament has been replaced by a carefully optimized microwave plasma (MP) cathode under the electron cyclotron resonance condition. Different geometries of antennae in which the microwave transverse electric field is more or less favored have been tested. A major improvement was obtained when a dc polarization of these antennae was superimposed onto the microwave field, allowing a fine tuning via the sheath thickness adjustment. Registered cathode currents under various conditions of pressure of neutrals, microwave power, and polarization voltage have shown a gain of a factor of 3 relative to the previous case where the single disk antenna was at a floating potential. Best results with argon gas at a pressure of 3×10−2 mbar were obtained with a spear-head shaped antenna fed at a microwave power of 50 W and polarized at 26 V. Extracted ion beam current densities as high as 5 mA/cm2 resulted from these different MP cathode improvements. Moreover, we have shown that the internal electronic tuning of the source can advantageously replace the traditional external tuning.
Some special microwave structures for ECRIS
Authors: Cojocaru G. , Martin D. , Ivanov E. , Braic V.
Published: July 2002

The studies and the experimental work for constructing an electron cyclotron resonance ion source (ECRIS) for the new tritium linear accelerator (TRILAC) at the Institute of Atomic Physics are presented. The absence of consumable parts, the low neutral pressure, and the high ionization efficiency with light elements make ECRIS very attractive for this accelerator. Some special configurations for the microwave system and for the plasma chamber are presented. A suitable modified structure of a power helix-type traveling wave tube (glass envelope with helix) in conjunction with its corresponding lateral rectangular waveguide tapers is presented. Application of an iris-loaded circular waveguide (traveling wave structure of a linear accelerator) as a slow wave structure is also under study. Problems like unstable tuning and arcing, which are encountered in the known structures, could be avoided by using slow wave structures of traveling wave type.
An application of a thermosensitive quartz resonator for liquid flow rate measurement
Authors: Spassov Lozan , Yankov Dimitar Y.
Published: July 2002

The temperature-frequency dependence of a thermosensitive quartz resonator is used for the measurement of liquid flow rate. Because of a special quartz cut the resonator has very high temperature sensitivity which allows very small temperature changes to be detected. Using a heater the resonator is heated to a temperature higher than the ambient temperature. The resonator and the heater are designed together as a measuring probe which is placed in the path of a flowing liquid. The liquid flow cools the resonator and causes a frequency change. Using another resonator the temperature difference between the temperatures of the heated resonator and the ambient liquid is measured. In a number of experiments the relationship between the resonator temperature and water flow rate is investigated. A theoretical analysis for this relationship is delivered too. It is found that when the water flow rate is varied from 0.1 to 1.4 m/s the resonator temperature changes within 15 °C.
Status of development of ECR ion sources at Grenoble (invited)
Authors: Melin G. , Bourg F. , Briand P. , Delaunay M. , Gaudart G. , Girard A. , Hitz D. , Klein J. P. , Ludwig P. , Nguyen T. K. , Pontonnier M. , Su Y.
Published: July 2002

This article gives a short summary of the performances of the electron cyclotron resonance ion sources (ECRIS) so far built by the Grenoble laboratory; emphasis is given to the high B field Caprice source, a compact in size source delivering high charge states and high intensities. Both the continuous regime of operation, and the pulsed regime having performances enhanced by the afterglow effect, as well as other noticeable effects, are surveyed. The next part of the article deals with the analysis of the data and our present understanding of the ECRIS behavior. At last the present trends of development of ECRIS are examined.
Long plasma generation using microwave slot antennas on a rectangular waveguide
Authors: Tahara Hirokazu , Kitayama Jiro , Yasui Toshiaki , Onoe Ken-ichi , Tsubakishita Yasuji , Yoshikawa Takao
Published: July 2002

30-cm-class long plasmas were generated using 2.45-GHz microwave slot antennas on a rectangular waveguide with a T-shaped ridge for the development of high performance ion sources or for plasma reactors for large-area material processing. The microwave coupling efficiencies above 85% were achieved for Ar, N2, and O2 over large flow rate ranges. From the electric fields on the inner wall E side of the waveguide, standing waves with the maximum electric field strength of about 30 kV/m were expected to be excited in the waveguide, depending on the location of the T-shaped ridge. The plasma density for Ar was in the order of 1017 m−3 and for N2 and O2 1016 m−3 in a discharge chamber in front of the slot antennas. The electron temperature for Ar ranged from 3 to 4 eV and for N2 and O2 from 3 to 8 eV. The spatial profiles of the ion saturation current for Ar were almost flat in the discharge chamber although the profiles for N2 and O2, with large flow rates or near the antennas, were slightly rough.
Precision terahertz relative reflectometry using a blackbody source and heterodyne receiver
Authors: Woskov P. P. , Cohn D. R. , Han S. C. , Gatesman A. , Giles R. H. , Waldman J.
Published: July 2002

Instrumentation for making localized, precise relative reflection measurements of metals and superconductors in the terahertz frequency range is demonstrated. The results can be used to determine the surface resistivity of these materials which is of particular importance to development of high-temperature superconductors. Emission from a commerically available 1000 °C blackbody source was reflected from the materials under test and a reference reflector. The reflected signals were detected by a Schottky diode heterodyne receiver using a CO2-laser-pumped 214.5 μm CH2F2 laser as the local oscillator. Double-sideband bandwidth and receiver noise temperature were 2 GHz and 30 000 K, respectively. The use of a broadband incoherent diagnostic source minimizes instrumentation sensitivity to coherent interference effects. The heterodyne receiver provides for sensitive detection with good spatial and frequency resolution. Unoptimized spatial resolution of four times the diffraction limit was achieved. The potential for relative reflectivity measurement accuracy of better than 0.1% was demonstrated with 30 min measurement times though systematic errors limited actual measurement accuracy to about 0.3%.
Performance analysis of a fiber optic accelerometer based on a compliant cylinder design
Authors: Pechstedt R. D. , Jackson D. A.
Published: July 2002

The performance of an all fiber accelerometer, based on a compliant cylinder design and operating at λ0=1.3 μm is described. Sub-μg/√Hz resolution in a frequency range from 10 to 250 Hz has been demonstrated. The measured dynamic range exceeds six orders of magnitude. Faraday rotation mirrors have been incorporated into the accelerometer to prevent signal fading due to random changes in the state of polarization of the guided beams. Test results at elevated temperatures are presented.
Concentration-depth profiling using total-reflection x-ray fluorescence spectrometry in combination with ion-beam microsectioning techniques
Authors: Wiener G. , Michaelsen C. , Knoth J. , Schwenke H. , Bormann R.
Published: July 2002

A new method for the determination of vertical concentration profiles and its application to bilayer diffusion couples are presented. The method combines sputter sectioning techniques with ex situ total-reflection x-ray fluorescence (TXRF) analysis. It allows quantitative depth-resolved analysis of alloys consisting of elements with atomic numbers ≥13, quantitatively and depth resolved. In contrast to other surface sensitive techniques like Auger electron spectrometry or secondary ion mass spectrometry, TXRF offers the advantage of determining the sampling depth with the same instrument, so that no assumptions about sputtering rates or auxiliary measurements are necessary. With this method a depth resolution of 2.5 nm is obtained, which is comparable with the best achievable results from other depth profiling methods. Moreover, an additional TXRF scan in a nondestructive mode of operation makes a mutual comparison with the results of the sectioning technique possible.
Production of an atomic oxygen beam by a nozzle-beam-type microwave radical source
Authors: Yoshida Yoshikazu , Okazaki Yasunao , Ito Katsuyuki , Mizuguchi Shin-Ichi
Published: July 2002

Characteristics of a nozzle-beam-type microwave radical source are described. This source generates microwave plasma in a space between a nozzle and a skimmer to excite a processing gas. The source has a nozzle of 0.6 mm aperture, followed by a 1.2 mm skimmer, and gases pass through the skimmer so that a molecular beam contains radicals. The total atomic oxygen flux is 1.8×1016 atoms/s at a power of 130 W and an O2 flow rate of 2 SCCM. It is possible to optimize the beam profile by varying the combination of the nozzle and the skimmer. Thus, a high-density radical source with a compact structure and low power consumption is realized. This source is promising for oxide film growth in an ultrahigh vacuum processing.
SIMION study of the fringing field effects in deflector-type electrostatic electron energy analyzers: A new flexible Jost-based correction scheme
Authors: Hu D. Q. , Leung K. T.
Published: July 2002

The common use of physical stops (such as slits and apertures) at the entrance and exit planes of a deflector-type electrostatic electron energy analyzer often introduces unwanted distortions in the ‘‘ideal’’ equipotential distribution and reduces the deflection angle. Since Herzog’s classic work on the fringing field correction, a variety of correction schemes have been devised. Most of these correction methods are not entirely satisfactory particularly for applications that require the use of position sensitive detectors (PSDs). In the present work, we investigate the effects of physical stops and Jost plates on the fringing field in a standard hemispherical energy analyzer by using the electron ray-tracing simulation program SIMION. By balancing the fringing field effect due to the physical stops with that of the Jost plates, we extend the correction scheme proposed earlier by Jost. The present correction scheme has the advantages of ease of construction and compatibility with PSDs.
Measurement of flow speed from video images of demixing liquid–liquid system using spatial–temporal Fourier spectral method
Authors: To Kiwing
Published: July 2002

A video imaging method for measuring motion by analyzing the optical flow of the video image sequence using spatial–temporal Fourier transform is presented. The principle of measuring motion in the spatial–temporal Fourier domain is given and its performance is studied by computer simulation. The feasibility of this technique in measuring the flow speed of a highly turbid demixing binary liquid mixture where conventional optical methods (such as PIV and LDA) cannot be used is demonstrated.
A zone plate soft x-ray microscope using monochromatized undulator radiation at the beamline NE1B of the TRISTAN Accumulation Ring
Authors: Wang J.-D. , Kagoshima Y. , Miyahara T. , Ando M. , Aoki S. , Anderson E. , Attwood D. , Kern D.
Published: July 2002

A soft x-ray microscope has been developed at the beamline NE1B of the 6.5-GeV TRISTAN Accumulation Ring (AR). It makes use of undulator radiation as its source and a zone plate with the outermost zone width of 50 nm as its imaging element. It has two main features. First, the undulator radiation is monochromatized by a grazing incidence grating monochromator to match to the monochromaticity requirement of the zone plate. Second, a visible light prefocus unit consisting of two objectives has been designed and installed in the x-ray microscope. The x-ray optical system of the microscope can be adjusted easily, quickly, and precisely by using this unit. The microscope can resolve 55-nm lines and spaces in a zone plate test pattern.
A charged-particle spectrometer for ρR measurements (abstract)a)
Authors: Li C. K. , Petrasso R. D. , Wenzel K. W. , Hicks D. , Knauer J. P.
Published: July 2002

We are developing an advanced electronic charged-particle spectrometer (a magnetic/CCD system) for ICF ρR measurements. Knock-on and other charged fusion products are bent by a magnetic field (about 1 T) in order to avoid line-of-sight x rays from directly impinging on the detector. The detector itself is a stack of four charge coupled devices (CCDs) sandwiched between ‘‘ranging filters’’. To avoid blooming effects in the CCDs, we plan to use only ‘‘thinned’’ CCDs, for which each element is ∼20 μm thick. (The CCD is supported by a silicon substrate of thickness ∼200 μm.) The CCDs are sandwiched between four aluminum filters which have two functions. The first filter reduces the background by completely ranging out select charged particles, such as 3.5 MeV α’s (range ≂13 μm). Also, the first filter, with a thickness ∼50 μm, severely attenuates scattered soft x rays and visible light. The following three filters are each ∼300 μm. The total thickness of these filters and CCDs (with support substrate) are about 2000 μm, a thickness which completely stops energetic protons up to ≂ 15 MeV. Equally important, the next three ranging filters downshift the particle energy, and this is reflected in increased energy deposition in the CCD (since dE/dx∼1/E, where E is the kinetic energy). With this spectrometer, a charged particle experiences four separate interactions with the CCDs and ranging filters: this allows the incident particle energy to be overdetermined and the particle to be uniquely identified. Furthermore, because the CCD has small picture elements (∼ 20 μm), pulse pileup can be avoided. A crucial tool in the development of this spectrometer is the MIT Cockcroft–Walton fusion product generator. This generator will be used to test and validate design concepts, study energetic particle trajectories through the magnetic field and through the detector stack, and to test and absolutely calibrate the response of this spectrometer to a variety of 0.5–15 MeV charged particles.
Thermal positive-ion source developed for molecular beam detection
Authors: Kawano Hiroyuki , Matsui Seiji , Serizawa Naoshi
Published: July 2002

A thermal positive-ion source developed for neutral beam detection has a filament (∼0.1 mm in diameter) of Re or W, which is surrounded with a cylinder. A beam of metal halide (MX) was directed onto a small area (S≊10−3 cm2) of the filament at a constant flux (N), and M+ emitted from the filament was collected mainly with the cylinder and partly (∼1%) with a Faraday cup. The ionization efficiency of both InI and TlI on Re in high vacuum (∼0.2 μTorr), for example, is unity in the optimum temperature range of ∼1000–1100 K mainly because the work function of Re under the above condition is as large as ∼7 eV, thereby yielding the ion current of ∼1 nA at N≊1012 molecules cm−2 s−1. Our experimental data and analytical results indicate that Re as well as W in the optimum range detects efficiently (∼100%) a beam of MX impinging at a net flux (NS) of more than ∼1010 molecules s−1 and yields ∼1 nA of M+ so long as the ionization energy of M is less than ∼6.4 eV. The data on the range are summarized together with experimental conditions employed.
Application of 6 MeV/n heavy-ion beams to biophysical experiments (abstract)a)
Authors: Sato Y. , Tanaka A. , Furusawa Y. , Matsumoto S. , Murakami K. , Soga F. , Takeo K. , Fujita Y.
Published: July 2002

A new facility using 6 MeV/n heavy-ion beams is described along with preliminary results of its applications to biophysical investigations. The beams are obtained at the terminal of the injector linac installed in the heavy-ion medical accelerator in Chiba. Various ion species (He–Xe) having different charge states are accelerated to the same velocity, which is suitable for comparing the charge effects of heavy ions. An attempt has been made for investigations of the track structure by using pBR322 plasmid DNA and spores as targets. Newly constructed equipment with the molecular beam source (H2O) placed on this beam line is also described.
Development of a surface ionization type dual-ion source applicable to ionic crystalline samples
Authors: Kawano Hiroyuki , Kamidoi Susumu , Shimizu Hironari
Published: July 2002

A surface ionization type dual-ion source (DIS) developed for ionic crystalline samples such as alkali halides (MX) consists of (1) a sample plate (F1, ∼0.02 cm2) heated up to ∼1000 K to produce primary ion (M+ or X−) by dissociative self-surface ionization of MX deposited on F1, (2) a second filament (F2) kept at 1260 K to produce secondary ion (M+) by molecular beam surface ionization of the neutral molecule (MX0) desorbing from F1 and (3) a grid (G) mounted between F1 and F2 to retard the primary and secondary ions. These ions are independently extracted efficiently and collected separately without using any separator other than G. Our DIS is free from background ions due to residual gases, easy in operation, simple in structure and small in size (∼2 cm3) but quite useful for kinetic studies of ionic and neutral desorption from MX and also for generating monochromatic and stable dual-ion beams (∼1 pA) from MX (∼1 μg) deposited on F1.
Recent ion source development in China (invited)
Authors: Chen Chia-erh , Zhao Weijiang
Published: July 2002

The recent development of various types of ion sources and their application in China is reviewed. Emphasis is given to new improvements of the electron cyclotron resonance ion source, MEVVA ion source, electron beam evaporation metal ion source, compact multicusp ion source, as well as compact negative ion sources with permanent magnets. Some of the new proposals are also presented.
Extraction of negative lithium ions from a lithium-containing hydrogen plasma
Authors: Wada Motoi , Sasao Mamiko
Published: July 2002

Negative lithium ions (Li−) were extracted from a 6-cm-diam 7-cm-long negative hydrogen ion (H−) source to simulate the condition of Li− extraction from a Li vapor introduced ion source for the neutral beam heating. The amount of the Li− current extracted from a hydrogen plasma with Li vapor was comparable to that extracted from a pure Li plasma. However, the amount of the H− current decreased as the H2 gas pressure in the source decreased due to a getter-pump effect of Li during the introduction of Li vapor. A heat shield installed to keep a high wall temperature was effective in mitigating the pressure decrease. However, the H− current extracted from the ion source equipped with the heat shield became 20% of the original value, as Li vapor was injected into the ion source.
High-current negative-ion sources for pulsed spallation neutron sources: LBNL Workshop, October 1994 (invited)
Authors: Alonso Jose R.
Published: July 2002

The neutron scattering community has endorsed the need for a high-power (1–5 MW) accelerator-driven source of neutrons for materials research. Properly configured, the accelerator could produce very short (submicrosecond) bursts of cold neutrons, said time structure offering advantages over the continuous flux from a reactor. The recent cancellation of the ANS reactor project has increased the urgency to develop a comprehensive strategy based on the best technological scenarios. Studies to date have built on the experience from ISIS (the 160 kW source in the UK), and call for a high-current (∼100 mA peak) H− source-linac combination injecting into one or more accumulator rings in which beam may be further accelerated. The 1–5 GeV proton beam is extracted in a single turn and brought to the target-moderator stations. The high current, high duty factor, high brightness and high reliability required of the ion source present a very large challenge to the ion source community. The Workshop reported on here, held in Berkeley in October 1994, analyzed in detail the source requirements for proposed accelerator scenarios, the present performance capabilities of different H− source technologies, and identified necessary R&D efforts to bridge the gap.
Laser ion source development at CERN
Authors: Collier J. , Hall G. , Haseroth H. , Kugler H. , Kuttenberger A. , Langbein K. , Scrivens R. , Sherwood T. R. , Tambini J. , Shamaev O. B. , Sharkov B. Yu. , Shumshurov A. , Kozochkin S. M. , Makarov K. N. , Satov Yu. A.
Published: July 2002

At CERN there is a demand for high currents of highly charged ions, presently for fixed target experiments at the SPS and in the future for the LHC project. The LHC, however, requires an intensity, which is an order of magnitude larger than the intensity presently achieved using an electron cyclotron resonance ion source. Laser ion sources have the potential to fulfill the LHC requirements, although a large number of technical problems have to be overcome. At CERN a project to investigate the feasibility of the application of laser ion sources was started in 1989 and a source capable of producing large currents of highly charged ions was constructed. The results of the investigations on this source, including charge state distributions, measurements of the energy distribution, measurements of ion currents, and emittance measurements will be presented. Furthermore a method to reduce the time-dependent energy change is described.
The Frankfurt MEDEBIS: A prototype of an injector for a synchrotron dedicated for cancer therapya)
Authors: Kester O. , Becker R. , Kleinod M.
Published: July 2002

The Frankfurt MEDEBIS has been constructed to study the techniques of an electron beam ion source (EBIS) designed as an injector for a synchrotron dedicated to cancer therapy. The MEDEBIS uses a normal conducting solenoid of 0.8 T and a trap length of 0.25 m. The aims are to inject fully stripped light ions like C6+ and O8+ in a single turn into a synchrotron for the most simple and reliable operation. Therefore fast ion extraction in less than 4 μs has been examined, both theoretically and experimentally. The source complexity has been reduced by iron shielding of an electron gun and collector without any bucking coils. The electron gun operates with partially immersed flow focusing and provides a maximum current density of about 70 A/cm2. With a second anode the beam perveance is variable. The ion extraction time is reduced by a novel electrostatic structure providing a pulsed extraction field along the axis of the whole ion trap. Measurements of extracted ion pulses and the total number of extracted charges are presented. At confinement times of about 200 ms bare nuclei are obtained with maximum abundance in the charge spectra in good agreement with design data and Lotz cross sections.
Vacuum arc gas/metal ion sources with a magnetic field
Authors: Oks Efim , Yushkov George , Schanin Peter , Nikolaev Alex
Published: July 2002

This types of vacuum arc ion source provides the generation of ions of various gases and metals. A specific feature of these ion sources is the use of two cold-cathode arc discharges to produce plasma for the extraction of ion beams. Metal ions are generated by means of a vacuum arc in the metal vapor produced by cathode spots. Gas ions are generated by a constricted low-pressure arc discharge. In this paper we discuss the problem as follows: the production of broad beams by extracting ions from the anode cavity in the transverse direction and the initiation of a vacuum arc cathode spot by an auxiliary discharge in a strong magnetic field.
The status of Deutsches Elektronen-Synchrotron H− sources
Authors: Peters J.
Published: July 2002

Two different types of H− sources are operated at Deutsches Elektronen Synchrotron, a magnetron source and an experimental rf-driven volume source. H− sources for HERA have to run for long uninterrupted periods with a low duty factor and a high reliability. Several necessary improvements are under construction for our rf-driven volume source. The status of both the magnetron and volume source will be discussed and the latest experimental data will be presented.
Development of a high brightness negative hydrogen ion source
Authors: Oguri H. , Okumura Y. , Miyamoto N. , Kusano J. , Mizumoto M.
Published: July 2002

A high brightness negative hydrogen ion source has been developed for a high intensity proton linear accelerator. The ion source is volume production type. Negative ions are generated in a magnetically filtered multicusp plasma generator. The negative ion production is enhanced by seeding a small amount of cesium into the plasma generator. A negative hydrogen ion beam of 36 mA was extracted from a single aperture at an acceleration voltage of 50 kV. To obtain a higher ion beam current, the focusing of beamlets extracted from the multiaperture grid has been demonstrated with an aperture displacement technique.
Development of a D+ source for International Fusion Materials Irradiation Facility
Authors: Maaser A. , Volk K. , Weber M. , Klein H.
Published: July 2002

A volume source, based on the high efficiency ion source (HIEFS), is being developed for D+ production in steady state operation. The source will be optimized for the extraction of atomic deuterium ions with high current densities. It was found that a maximum deuterium ion beam current density of 210 mA/cm2 can be achieved with a D+ fraction above 90%. At an extraction voltage of 35 kV and with an aperture radius of 4 mm, the source delivers 61 mA D+. After a description of the source and the experimental setup, the results of detailed studies of the beam composition in dependence of the plasma parameters are presented.
Performance characterization of rf-driven multicusp ion sources
Authors: Perkins L. T. , De Vries G. J. , Herz P. R. , Kunkel W. B. , Leung K. N. , Pickard D. S. , Wengrow A. , Williams M. D.
Published: July 2002

Radio-frequency (rf)-driven multicusp ion sources have been developed extensively at Lawrence Berkeley National Laboratory (LBNL) for many applications, each requiring specific source designs. These uses have ranged from large ion sources for neutral-beam injectors—several tens of centimeters in size—to small sources for oil-well logging neutron tubes—a few centimeters in diameter. The advantages associated with internal antenna, rf-driven ion sources include reliability, long component life, ease of operation, and the ability to generate plasmas free of the impurities commonly found in hot-filament discharge sources. We have investigated and characterized the performance of rf-driven sources with respect to the rf operating frequency and ion source size for hydrogen ion species and current density. Furthermore, we have included in this study the aspects of proper coupling of the rf generator to the antenna through an impedance matching network. Finally, critical issues pertaining to general rf operation including beam extraction, rf shielding, and cooling of transformer cores are discussed.
Numerical simulation of ion-beam formation (invited)
Authors: Becker Reinard
Published: July 2002

The methods of numerical simulation of particle optics problems are examined with respect to their accuracy and stability. Principles of space-charge optics and of beam formation are recalled to address questions like the general validity of the 3/2-power law and the Pierce angle. For the simplest mathematical model of the plasma sheath the ‘‘correct’’ shape of the wall electrode is calculated analytically and compared with numerical simulations. The result will be used to establish engineering rules for the extraction of ion beams from a plasma with minimum aberration. The compensation of ion beams by electrons and the influence of this on ion-beam formation is discussed both from the viewpoint of theoretical analysis of compensation as well as on the basis of experimental evidence.
Review of work related to ion sources and targets for radioactive beams at Argonne
Authors: Nolen J. A.
Published: July 2002

A group including many ANL Physics Division staff and ATLAS outside users has discussed possibilities for research with radioactive ion beams and prepared a working paper entitled ‘‘Concept for an Advanced Exotic Beam Facility Based on ATLAS.’’ Several subgroups have been working on issues related to ion sources and targets which could be used in the production and ionization of radionuclides with high power primary beams. Present activities include: (a) setting up an ion source test stand to measure emittances and energy spreads of ISOL-type ion sources, (b) experiments to evaluate methods of containing liquid uranium for production targets, (c) experimental evaluation of geometries for the generation of secondary neutron beams for production of radionuclides, (d) setting up an ISOL-type ion source at a neutron generator facility to measure fission fragment release times and efficiencies, and (e) computer simulations of an electron-beam charge-state amplifier to increase the charge states of 1+ secondary beams to 2, 3, or 4+. The present status of these projects and future plans are presented in this report.
Nonintrusive fast response concentration measurement device for chemical reactors
Authors: Nadeau P. , Berk D. , Munz R. J.
Published: July 2002

A device is proposed by which the residence time distribution in a tubular chemical reactor can be measured with a response time on the order of hundreds of microseconds. This device works on the principle of infrared laser absorption spectroscopy. Because the light beam passes directly through the reactor cross section, there is no measurement cell thus making the technique nonintrusive. The device has been successfully tested with a tubular reactor with a gaseous flow at average residence times ranging from 0.04 to 0.7 s. The level of micromixing in the reactor can also be estimated due to the very fast response of the instrument.
Time-resolved electron spectrum diagnostics for a free-electron laser
Authors: Gillespie W. A. , MacLeod A. M. , Martin P. F. , van der Meer A. F. G. , van Amersfoort P. W.
Published: July 2002

Time-resolved electron-beam diagnostics have been developed for use with free-electron lasers (FELs) and associated electron sources, based on the techniques of secondary electron emission and optical transition radiation (OTR). The 32-channel OTR detector forms part of a high-resolution (0.18%) electron spectrometer with a time resolution of 50 ns. Variable-magnification optics allow the spectrometer to view single-macropulse spectra with widths in the range of 0.2%–7%; wider spectra are taken with several momentum settings. Design criteria for the spectrometer are presented, and experience of operating with the diagnostics over a range of FEL physics experiments is summarized. The spectrometer is used, in conjunction with optical diagnostics, in studies at FELIX of efficiency enhancement, pulse chirping, and stepped-undulator operation.
Hard x-ray detector based on microchannel plates
Authors: Shikhaliev P. M.
Published: July 2002

A high efficiency detector of hard x ray based on microchannel plates is described. The detected x-ray beam was directed perpendicularly to the lateral surface of microchannel plate convertors. The detection efficiency for beams with 2×2 mm cross section and energies of 662 and 122 keV was 24% and 35%, respectively. The probability of x-ray interaction with microchannel plate material was measured. The detector position resolution is 0.5 and 1.5 mm for 122 and 662 keV radiation.
Energetic negative ion source for fusion at NIFS (invited)
Authors: Kuroda T. , Kaneko O. , Takeiri Y. , Oka Y. , Tsumori K. , Asano E. , Kawamoto T. , Akiyama R. , Ando A. , Takanashi T. , Hamabe M.
Published: July 2002

Large high current hydrogen negative ion sources have been developed for the negative ion based neutral beam injector of the Large Helical Device (LHD) at NIFS. The prototype of the negative ion source is required to deliver a negative ion beam of 45 A at the beam energy of 125 keV. The optimization of 1/3 scale ion sources which are multicusp ion source with a rod and an external magnetic filter, respectively, has been investigated for the operation parameter of the plasma source. A total H− current of 16 A is extracted at an operating pressure of 0.9–0.45 Pa with Cs seeding operation. Negative hydrogen ion current is proportional to the input arc power and a beam current density of 45 mA/cm2 is attained. The beam extraction and acceleration characteristics are studied for a single-stage and a two-stage acceleration electrode. A beam divergence angle of 5 mrad is obtained. The results of research and development of a hydrogen negative ion source at NIFS will be reviewed.
Sensitive interferometric video thermal wave imager
Authors: Power J. F.
Published: July 2002

A new method of parallel thermal wave imaging is demonstrated in which the thermal wave image of a heated sample is converted into an optical phase image which is sensitively probed by a Twyman–Green interferometer. The sample is mounted onto an assembly of optical layers which acts as a temperature sensitive mirror. Heat conduction from the sample to this mirror results in a two-dimensional distribution of optical phase which is probed broadfield by the interferometer. The resulting transmission thermal wave image has characteristics analogous to those of photopyroelectric images. The interferogram produced in the interferometer may be recorded by videography, although rapid frame processing methods will be required for the full advantages of the method to be realized.
Determination of concentration depth profiles using total-reflection x-ray fluorescence spectrometry in combination with ion-beam etching
Authors: Günther R. , Wiener G. , Knoth J. , Schwenke H. , Bormann R.
Published: July 2002

A new method for quantitative concentration depth profiling is presented. It combines a sputter-etching technique with ex situ total-reflection x-ray fluorescence analysis. It allows quantitative depth-resolved analysis of alloys consisting of elements with atomic number ≥13. Basic requirements for a high depth resolution are reported. With this method, an experimental depth resolution of 1.4 (±0.4) nm is obtained that is comparable with the best achievable results from other depth profiling methods.
Thermopower measurements in magnetic fields up to 17 tesla using the toggled heating method
Authors: Resel R. , Gratz E. , Burkov A. T. , Nakama T. , Higa M. , Yagasaki K.
Published: July 2002

A dc method for thermopower (TP) measurements in magnetic fields up to 17 T in the temperature range from 3 K to 300 K is introduced. A special heating technique named ‘‘seesaw heating,’’ a method similar to ac methods, was developed and resulted in good thermal stability, better accuracy and a faster procedure. Chromel–constantan thermocouples were utilized for measuring probes because of small and simple temperature dependence of magnetic field effect. Finding an empirical formula for all the calibration curves of TP of Chromel enable us to measure TP at any field and at any temperature. Finally, the experimental results on ErCo2 and LaRu2 are presented as test examples to demonstrate the possibilities and accuracy of our setup.
A miniaturized reactor for photocatalysis and for simultaneous in situ spectroscopy
Authors: Saladin F. , Meier A. , Kamber I.
Published: July 2002

The design of a miniaturized photoreactor is presented that allows for continuous as well as for stopped flow photochemical experiments on solid photocatalysts with gaseous educts. Volatile products can be analyzed by any gas phase detection scheme such as mass spectrometry or gas chromatography. In addition, the design allows for easy in situ optical spectroscopic measurements such as UV/VIS, IR, and luminescence, depending on the transparency of the window material used.
The use of strain gauges to measure low velocity fluid flow
Authors: Roland Paul A.
Published: July 2002

A device was designed, built, calibrated, and installed in a small shallow lake for the detection and measurement of water movement at low velocities in natural environments. The device used sets of typical strain gauges in a full-bridge configuration positioned orthogonally with respect to each other and in an array to receive multiple signals. Standard analog to digital detection and recording, via simple computing techniques, was used. This article also reports the first directly measured slow flow directionality of shallow water movement in the three coordinate system and its conversion to cylindrical and spherical systems.
LiNbO3 composite oscillator for internal friction and modulus measurement at elevated temperatures
Authors: Ozawa Masakuni , Inagaki Masahiko , Suzuki Suguru
Published: July 2002

We describe a longitudinal LiNbO3 composite oscillator at 100–300 kHz to measure internal friction and Young’s modulus of a small sample bar, which is directly heated in a furnace at elevated temperatures up to 800 °C. Resonant frequency, mechanical loss, and electric conductivity of a fabricated LiNbO3 oscillator are measured as a function of temperature. The present method is successfully applied to YBa2Cu3O6+x wires with 1 mm diameter and 7 mm length at 30–800 °C.
Damages to B4C/W multilayer mirrors by intense soft x-ray bursts
Authors: Le Guern F. , Troussel P. , André J.-M. , Friart D. , Jalinaud T. , Rabec le Gloahec M. , Desenne D. , Le Breton J.-P. , Boutin J.-Y. , Dutrannoy J.-L. , Nazet C. , Davi P. , Barchewitz R.
Published: July 2002

B4C/W multilayer mirrors designed for an x-ray beamline at the MEGAJOULE facility are susceptible to x-ray damage. The OCTAL laser was implemented to generate a gold plasma with a continuous x-ray spectrum (0.1 to 1.5 keV) used to irradiate the mirror. The fluence on the sample is 0.05 J/cm2 per shot. The pulse duration is about 1 ns. The temporally integrated spectrum reflected by the mirror is analyzed by a bent crystal spectrometer and recorded on photographic film. The spectral analysis suggests that an increase of the mean period of the multilayer happens during the second shot. This expansion is estimated to be 5% with respect to the unexposed mirror. After the second shot, destruction of the multilayer coating in the central part of the sample and irreversible damages in the other part characterized by a decrease of Bragg reflectivity have been observed.
Controlled production of warm electron beams
Authors: Doveil F. , Tsunoda S. I. , Malmberg J. H.
Published: July 2002

A warm beam is produced by passing a cold electron beam through a system of three closely spaced parallel grids. The beam and the grid structure are immersed in a magnetic field. The middle grid is biased at a large positive potential, and the resulting electric field near the grid wires scatters part of the electrons axial energy into transverse energy. Thus, although the beam remains monoenergetic, a controllable spread in both the transverse and axial energy distribution is obtained.
Two port cavity Q measurement using scattering parameters
Authors: Han Dae-Hyun , Kim Young-Soo , Kwon M.
Published: July 2002

A method of measuring Q of a two port cavity by scattering parameters is described. The scattering parameters of a two port cavity resonator are derived by a lumped equivalent circuit model as a function of cavity parameters, including the cavity Q. These can be also obtained by direct measurement with a modern network analyzer. The results agree well with those from other well-known methods. This two port measurement can provide additional information such as the coupled power ratio, which is one of the important parameters for the beam-accelerating cavities.
Uranium-233 fission detectors for neutron flux measurement in reactors
Authors: Prasad K. R. , Balagi V.
Published: July 2002

Fission counters have been developed indigenously, using 233U as a sensing material for reactor startup applications. The first model has a counting sensitivity of 0.003 cps/nv in the pulse mode, 1×10−15 A/nv in the dc mode, and 6.4×10−29 A2 Hz/nv in the Campbell mode. A more sensitive counter with about 75 mg of 233U showed an average sensitivity of 0.02 cps/nv. A proposal for 233U in-core miniature dc fission chambers is discussed. A design for high sensitivity (0.5 cps/nv) U-233 pulse counter with transmission line-type readout is also proposed.
Bolometric diagnostics in Tokamak de Varennes
Authors: Richard N. , Sarkissian A. H. , Drolet Y. , Ernst S. , St.-Germain J.-P
Published: July 2002

Radiative power from the main and divertor plasmas of Tokamak de Varennes (TdeV) is measured using a compact bolometric diagnostic. The diagnostic is comprised of a multichannel pin-hole camera and several collimated bolometers. The electronic circuit of the bolometers permits remotely controlled in situ calibration of the detectors. The pin-hole camera, with its 17 channels of thermistor bolometers, monitors the plasma poloidal cross section horizontally. In the same camera housing reside a pair of wide angle metal film bolometers that measure the total radiative losses from the main plasma, and a 16 channel x-ray-ultraviolet photodiode array. Five collimated thermistor bolometers project the vertical view of the plasma poloidal cross section. The divertor plasma losses are monitored by six pairs of collimated thermistor bolometers installed at different toroidal locations. One pair in the lower and three pairs in the upper divertor chamber measure the global power loss from the plasma in front of the outboard divertor plates. Two other pairs of bolometers located just behind the inclined divertor plate, measure the poloidal distribution of the plasma losses from the divertor plate to the X point with an improved spatial resolution. Three divertor bolometers and one of the wide angle bolometers in the main plasma are covered with MgF2 windows, for rough spectral analysis of the radiative power loss. Examples of bolometric measurements of the radiative loss and its distribution in the TdeV during plasma detachment, plasma biasing and lower hybrid current drive and heating experiments are given.
A combined thermal dissociation and electron impact ionization source for radioactive ion beam generation (abstract)a)
Authors: Alton G. D. , Williams C.
Published: July 2002

The probability for simultaneously dissociating and efficiently ionizing the individual atomic constituents of molecular feed materials with conventional, hot-cathode, electron-impact ion sources is low and consequently, the ion beams from these sources often appear as mixtures of several molecular sideband beams. This fragmentation process leads to dilution of the intensity of the species of interest for radioactive ion beam (RIB) applications where beam intensity is at a premium. We have conceived an ion source that combines the excellent molecular dissociation properties of a thermal dissociator and the high ionization efficiency characteristics of an electron impact ionization source that will, in principle, overcome this handicap. The source concept will be evaluated as a potential candidate for use for RIB generation at the Holifield Radioactive Ion Beam Facility, now under construction at the Oak Ridge National Laboratory. The design features and principles of operation of the source are described in this article.
Summary of 12th international ECRIS workshop [1995] (invited) (abstract)a)
Authors: Sekiguchi M.
Published: July 2002

The 12th international workshop on electron cyclotron resonance ion sources (ECRIS), held on 25–27, April 1995, is summarized from the following points of view: (1) steady improvement of performance, (2) better understanding of the physical processes upon which ECR ion sources are based, (3) active pursuit for better performance by using higher magnetic field and devising new technologies, and (4) expanding application of ECRIS for highly charged ions. The upper limit of performance has not been foreseen and further improvement can be expected.
Operation of a cw rf driven ion source with hydrogen and deuterium gas (abstract)
Authors: Melnychuk S. T. , Debiak T. W. , Sredniawski J. J.
Published: July 2002

We will describe the operation of a cw rf driven multicusp ion source designed for extraction of high current hydrogen and deuterium beams. The source is driven at 2 MHz by a 2.5 turn induction antenna immersed in the plasma. Bare stainless-steel and porcelain-coated Cu antennas have been used. The plasma load is matched to the rf generator by a variable tap N:1 transformer isolated to 46 kV, and an LC network on the secondary. With H2 gas the source can be operated at pressures between 5 and 60 mT with power reflection coefficients <0.01. The extracted ion current density with a porcelain-coated antenna is approximately given by 35 mA/cm2/kW with an 80 G dipole filter field for input powers from 3.5 to 6.6 kW. The current density remained constant for operation with a 6 and an 8 mm aperture. The source has been operated for 260 h at 3.6 kW with a single-porcelain-coated antenna. Mass spectrometer measurements of the extracted beam at this power show a species mix for H+:H+2:H+3:OH+ of 0.49: 0.04: 0.42: 0.04. The calculated beam divergence using the IGUN code is compared with the measured divergence from an electrostatic sweep emittance scanner designed for high-power cw beam diagnostics. Phase space measurements at 40 kV and 23 mA beam current result in a normalized rms emittance of 0.09 π mm mrad.
Use of ion sources for highly charged ions in studies of atomic and ion–solid collisions (invited) (abstract)
Authors: Winter H.
Published: July 2002

Collisions of slow multicharged and highly charged ions, i.e., ions with kinetic energies up to some 10 keV, with atoms in the gas phase and with solids have been studied in detail over the last few years. A brief review is presented on some typical experiments and their results which make use of the specific features of highly charged ions in the fields of atomic spectroscopy, ion–atom collisions, and ion–solid interactions. In particular recent progress in the understanding of the interaction mechanisms of highly charged ions with solid surfaces will be discussed.
XOP: A graphical user interface for spectral calculations and x-ray optics utilities
Authors: Dejus Roger J. , Sanchez del Rio Manuel
Published: July 2002

A graphical user interface, using the Interactive Data Language (IDL) widget toolkit, for calculation of spectral properties of synchrotron radiation sources and for interaction of x-rays with optical elements has been developed. The interface runs presently on three different computer architectures under the Unix operating system – the Sun-OS, the HP-UX, and the DEC-Unix operating systems. The point-and-click interface is used as a driver program for a variety of codes from different authors written in different computer languages. The execution of codes for calculating synchrotron radiation from undulators, wigglers, and bending magnets is summarized. The computation of optical properties of materials and the x-ray diffraction profiles from crystals in different geometries are also discussed. The interface largely simplifies the use of these codes and may be used without prior knowledge of how to run a particular program.