bluuebunny/crossref_metadata_2025 huggingface dataset:
Novel Acrylic‐modified Acacia Gum Thickener: Preparation, Characterization and Rheological Properties
Authors: Nickzare Morteza , Zohuriaan‐Mehr Mohammad J. , Yousefi Ali A. , Ershad‐Langroudi Amir
Published: March 2009

Acacia gum (Arabic gum; A‐gum) is a branched complex heteropolysaccharide with extremely high solubility and extraordinary Newtonian behavior in solution at concentrations even higher than 25%. In this work, A‐gum thickening properties were highly improved to form non‐Newtonian fluids in water at concentrations below 2%. The thickener was prepared by graft copolymerization of acrylonitrile onto A‐gum using ceric ammonium nitrate. The synthesized graft copolymers (differing in percentage and molecular weight of the grafted acrylic chains) were then alkaline‐hydrolyzed under various conditions (i.e. temperature, time and the NaOH concentration) to prepare the thickening agents. FTIR and elemental analyses were used for elucidating the structure of samples. Steady‐shear rheological properties of aqueous solutions of the thickener at variety of concentrations, temperatures and saline solutions were investigated in details.
Spectroscopic Characterisation of Cationic Quaternary Ammonium Starches
Authors: Pigorsch Enrico
Published: March 2009

Near‐infrared, infrared and Raman spectra of native starch and cationic quaternary ammonium starches prepared by different reaction methods were recorded. An interpretation of the spectra is given that takes the structural changes of the starch molecules and the degree of substitution (DS) into consideration. The near‐infrared spectra of the cationic starches showed additional bands compared to native starch at about 6010 cm−1 and 4438 cm−1, which are assigned to the first overtone of the stretching vibration and to a combination band of the CH3 groups in the trimethyl ammonium substituent. No significant changes in the infrared spectra of the cationic starches could be observed due to strong absorption bands of OH and H2O. By contrast, the Raman spectra of the cationic starches showed characteristic bands of the trimethyl ammonium substituent at about 3030, 970 and 761 cm−1. Plots of the ratios of intensity of the 761 cm−1 band to an unchanged starch band at 938 cm−1 versus DS gave linear curves which could be used for DS determination. Furthermore, the use of a NIR calibration model for DS determination with a standard error of calibration (SECV) of 0.003 is reported.
Monophosphorylation of Acid‐thinned Starch to Enhance the Quality of Viscose Yarns Sized at Reduced Temperature
Authors: Zhu Zhifeng , Liu Zhijun
Published: March 2009

Acid‐thinned cornstarch was monophosphorylated by reaction with orthophosphates to obtain an agent for sizing heat‐sensitive viscose warp yarns under reduced temperature. Influences of the modification and sizing temperature on paste behavior, adhesion to viscose fibers, and properties of sized viscose yarns were studied for a range of substitution of 0.021–0.082 and temperatures from 60°C to 95°C. The modification resulted in an increase in viscosity stability of the starch paste, enhancement of the adhesion to the viscose fibers, improvement of mechanical properties of the sized viscose yarns, and a decrease in hairiness of sized yarns even if the temperature of the starch paste was lowered to 60°C. The modification is capable of improving the sizing properties of starch for viscose yarns at 60–80°C when the degree of substitution with phosphate groups is about 0.05.
Does teaching experience matter? Examining biology teachers' prior knowledge for teaching in an alternative certification program
Authors: Friedrichsen Patricia J. , Abell Sandra K. , Pareja Enrique M. , Brown Patrick L. , Lankford Deanna M. , Volkmann Mark J.
Published: March 2009

Alternative certification programs (ACPs) have been proposed as a viable way to address teacher shortages, yet we know little about how teacher knowledge develops within such programs. The purpose of this study was to investigate prior knowledge for teaching among students entering an ACP, comparing individuals with teaching experience to those lacking teaching experience. Of the four participants seeking secondary biology teaching certification, two participants had 2 years of prior biology teaching experience. We used the Lesson Preparation Method as a data collection tool, asking participants to create lesson plans to teach the concept of heritable variation. Primary data sources were the lesson plans and follow‐up interview transcripts. Prior teaching experience made little difference as both groups held didactic teaching orientations and wrote similar lesson plans. Both groups drew on general pedagogical knowledge (PK), and had little pedagogical content knowledge for teaching heritable variation. Teaching experience did appear to lead to more integration among PK components. The study includes implications for the teacher education, research, and policy. © 2009 Wiley Periodicals, Inc. J Res Sci Teach 46: 357–383, 2009
Research education of new scientists: Implications for science teacher education
Authors: Feldman Allan , Divoll Kent , Rogan‐Klyve Allyson
Published: March 2009

This study examined an interdisciplinary scientific research project to understand how graduate and undergraduate honors students learn to do science. It was found that the education of the students occurs as part of an apprenticeship. The apprenticeship takes place in research groups. In general, research groups are structured in two ways: loosely organized and tightly organized, and have characteristics of both communities of practice and epistemic communities. Students have different roles in the research groups: novice researcher, proficient technician, or knowledge producer. Their role depends on their knowledge and skills, and their degree programs. It is possible for students to develop expertise along a continuum from novice researcher to knowledge producer. The members of the research group, including the professor and other students, facilitate the development of the students along the continuum of roles. Implications for the education of science teachers are discussed. © 2009 Wiley Periodicals, Inc. J Res Sci Teach 46: 442–459, 2009
Aluminum induces chromosome aberrations, micronuclei, and cell cycle dysfunction in root cells of Vicia faba
Authors: Yi Min , Yi Huilan , Li Honghai , Wu Lihua
Published: March 2009

Aluminum (Al) exists naturally in air, water, and soil, and also in our diet. Al can be absorbed into the human body and accumulates in different tissues, which has been linked to the occurrence of Alzheimer's disease and various neurological disorders. By using Vicia cytogenetic tests, which are commonly used to monitor the genotoxicity of environmental pollutants, cytogenetic effects of aluminum (AlCl3) were investigated in this study. Present results showed that Al caused significant increases in the frequencies of micronuclei (MN) and anaphase chromosome aberrations in Vicia faba root tips exposed to Al over a concentration‐tested range of 0.01–10 mM for 12 h. The frequency of micronucleated cells was higher in Al‐treated groups at pH 4.5 than that at pH 5.8. Similarly, AlCl3 treatment caused a decrease in the number of mitotic cells in a dose‐ and pH‐dependent manner. The number of cells in each mitotic phase changed in Al‐treated samples. Mitotic indices (MI) decreased with the increases of pycnotic cells. Our results demonstrate that aluminum chloride is a clear clastogenic/genotoxic and cytotoxic agent in Vicia root cells. The V. faba cytogenetic test could be used for the genotoxicity monitoring of aluminum water contamination. © 2009 Wiley Periodicals, Inc. Environ Toxicol, 2010.
Enhanced low‐cost RFID protocol to detect relay attacks
Authors: Munilla Jorge , Peinado Alberto
Published: March 2009

Contactless smart cards are more and more used in access control and payment systems. However, most of such cards are vulnerable to relay attacks, also known as mafia fraud attacks. This attack requires simpler technical resources than tampering or cryptanalysis. In this the adversary deceives, the verifier into thinking that a genuine prover is close by relaying the messages between both genuine parties. The main countermeasure against this attack is the use of so‐called distance bounding protocols. In the radio frequency identification (RFID) framework, Hancke and Kuhn proposed the first distance bounding protocol, which resorts to an expensive and complex ultra wide band (UWB) radio link. Reid et al. remove this extra radio link and propose a low‐cost protocol, but some aspects still need to be further investigated. In this paper, we propose an enhanced low‐cost protocol which takes advantage of the special characteristics of the inductive communication in RFID, and the use of ‘void‐challenges’ to protect against relay attacks. The processing delay of this protocol is zero and it can be directly implemented on RFID devices, without resorting to any extra resources. We present experimental results to support our arguments. Copyright © 2009 John Wiley & Sons, Ltd.
Predictive Factors for Morbidity and Mortality in Patients Undergoing Laparoscopic Paraesophageal Hernia Repair: Age, ASA Score and Operation Type Influence Morbidity
Authors: Larusson Hannes J. , Zingg Urs , Hahnloser Dieter , Delport Karen , Seifert Burkhardt , Oertli Daniel
Published: March 2009

Background

Patients undergoing laparoscopic paraesophageal hernia (PEH) repair risk substantial morbidity. The aim of the present study was to analyze predictive factors for postoperative morbidity and mortality.

Methods

A total of 354 laparoscopic PEH repairs were analyzed from the database of the Swiss Association for Laparoscopic and Thoracoscopic Surgery (SALTS). Age (<70 and ≥70 years) and risk (low: American Society of Anesthesiologists (ASA) scores 1 + 2; high ASA scores 3 + 4) groups were defined and multivariate logistic regression was conducted.

Results

In patients ≥70 years of age postoperative morbidity (24.4% versus 10.1%; p = 0.001) and mortality (2.4% versus 0%; p = 0.045) were significantly higher than in patients <70 years of age. In patients with gastropexy, this significant age difference was again present (38.8% versus 10.5%; p = 0.001) whereas in patients with fundoplication no difference between age groups occurred (11.9% versus 10.1%; p = 0.65). Mortality did not differ. High‐risk patients had a significantly higher morbidity (26.0% versus 11.2%; p = 0.001) but not mortality (2.1% versus 0.4%; p = 0.18). The multivariate logistic regression identified the following variables as influencing postoperative morbidity: Age ≥70 years (Odds Ratio [OR] 1.99 [95% CI 1.06 to 3.74], p = 0.033); ASA 3 + 4 (OR 2.29 [95% Confidence Interval (CI) 1.22 to 4.3]; p = 0.010); type of operation (gastropexy) (OR 2.36 [95% CI 1.27 to 4.37]; p = 0.006).

Conclusions

In patients undergoing laparoscopic paraesophageal hernia repair age, ASA score, and type of operation significantly influence postoperative morbidity and mortality. Morbidity is substantial among elderly patients and those with co‐morbidity, questioning the paradigm for surgery in all patients. The indication for surgery must be carefully balanced against the individual patient’s co‐morbidities, age, and symptoms, and the potentially life threatening complications.
Subsampling photographic capture‐recapture data of tigers (Panthera tigris) to minimize closure violation and improve estimate precision: a case study
Authors: Harihar Abishek , Pandav Bivash , Goyal Surendra Prakash
Published: March 2009

Most studies using photographic capture‐recapture methodology estimate parameters of interest with ecological and sampling uncertainties. However, the effect of sampling effort on assumption violation and estimate precision has seldom been described using empirical data in studies estimating population size of tigers (Panthera tigris tigris). In this study, we evaluate the influence of trap effort (trap area, mean cell area and trap density) on the assumption of geographic closure and their relationship with estimated capture probability. We do this by subsampling capture histories obtained for tigers from 30 trapping stations within the Chilla range of Rajaji National Park, India. We assessed the importance of trapping effort on geographic closure by estimating fidelity () and immigration () under the Pradel model. Estimate precision (CV% []) was evaluated based on estimates of capture probability (). Results of the Pradel analysis suggested that larger trap area (TA) ensured geographic closure, while high trap densities (TD) exhibited sex‐specific heterogeneity in recapture probabilities p. Simulation results suggested a significant positive correlation between estimates of () and TD. With increase in estimated capture probability, estimate precision (CV% []) also improved sharply. Comparison of prior studies towards optimizing sampling strategies is often compromised due to the difference in scale and methods of sampling. Therefore, we urge that subsampling within a dataset as illustrated in our study may prove to be an advantageous step towards standardizing photographic capture‐recapture sampling methodology for management objectives.
Preparation of Ultrafine Fe–Pt Alloy and Au Nanoparticle Colloids by KrF Excimer Laser Solution Photolysis
Authors: Watanabe Masato , Takamura Hitoshi , Sugai Hiroshi
Published: March 2009

We prepared ultrafine Fe–Pt alloy nanoparticle colloids by UV laser solution photolysis (KrF excimer laser of 248 nm wavelength) using precursors of methanol solutions into which iron and platinum complexes were dissolved together with PVP dispersant to prevent aggregations. From TEM observations, the Fe–Pt nanoparticles were found to be composed of disordered FCC A1 phase with average diameters of 0.5–3 nm regardless of the preparation conditions. Higher iron compositions of nanoparticles require irradiations of higher laser pulse energies typically more than 350 mJ, which is considered to be due to the difficulty in dissociation of Fe(III) acetylacetonate compared with Pt(II) acetylacetonate. Au colloid preparation by the same method was also attempted, resulting in Au nanoparticle colloids with over 10 times larger diameters than the Fe–Pt nanoparticles and UV–visible absorption peaks around 530 nm that originate from the surface plasmon resonance. Differences between the Fe–Pt and Au nanoparticles prepared by the KrF excimer laser solution photolysis are also discussed.
Oligofructose and inulin modulate glucose and amino acid metabolism through propionate production in normal-weight and obese cats
Authors: Verbrugghe Adronie , Hesta Myriam , Gommeren Kris , Daminet Sylvie , Wuyts Birgitte , Buyse Johan , Janssens Geert P. J.
Published: March 2009

The effect of dietary oligofructose and inulin supplementation on glucose metabolism in obese and non-obese cats was assessed. Two diets were tested in a crossover design; a control diet high in protein (46 % on DM basis), moderate in fat (15 %), low in carbohydrates (27 %), but no soluble fibres added; and a prebiotic diet, with 2·5 % of a mixture of oligofructose and inulin added to the control diet. Eight non-obese and eight obese cats were allotted to each of two diets in random order at intervals of 4 weeks. At the end of each testing period, intravenous glucose tolerance tests were performed. Area under the glucose curve (AUCgluc) was increased (P = 0·022) and the second insulin peak was delayed (P = 0·009) in obese compared to non-obese cats. Diets did not affect fasting plasma glucose concentrations, blood glucose response at each glucose time-point after glucose administration, AUCgluc, fasting serum insulin concentrations, area under the insulin curve, and height and appearance time of insulin response. Yet, analysis of acylcarnitines revealed higher propionylcarnitine concentrations (P = 0·03) when fed the prebiotic diet, suggesting colonic fermentation and propionate absorption. Prebiotic supplementation reduced methylmalonylcarnitine (P = 0·072) and aspartate aminotransferase concentrations (P = 0·025), both indicating reduced gluconeogenesis from amino acids. This trial evidenced impaired glucose tolerance and altered insulin response to glucose administration in obese compared to non-obese cats, regardless of dietary intervention; yet modulation of glucose metabolism by enhancing gluconeogenesis from propionate and inhibition of amino acid catabolism can be suggested.
Dehydroepiandrosterone activates cyclic adenosine 3′,5′-monophosphate/protein kinase A signalling and suppresses sterol regulatory element-binding protein-1 expression in cultured primary chicken hepatocytes
Authors: Tang Xue , Ma Haitian , Shen Zanming , Zou Sixiang , Xu Xijie , Lin Chengzhao
Published: March 2009

Dehydroepiandrosterone (DHEA), a steroid hormone that is secreted by the adrenal cortex in mammals, has an array of biological actions, including inhibition of fat synthesis, decreasing the number of adipocytes, and a reduction in mammalian metabolic efficiency. Recent studies showed that DHEA may decrease fat deposition in poultry, but the mechanism of action is unclear. In the present study, we demonstrate that DHEA stimulates intracellular cyclic adenosine 3′,5′-monophosphate (cAMP) accumulation in chicken hepatocytes during a 30 min incubation period. Increases in intracellular cAMP are evoked by as low as 0·1 μm-DHEA. The cAMP induced by DHEA, while suppressing cAMP-specific phosphodiesterase activity, also activates cAMP-dependent protein kinase A (PKA) in chicken hepatocytes. In addition, the activation of PKA leads to down-regulation of sterol regulatory element-binding protein-1 (SREBP-1). These findings demonstrate that direct action by DHEA leads to activation of the cAMP/PKA signalling system in the modulation of lipid metabolism by repressing SREBP-1, thereby providing a novel explanation for some of the underlying effects proposed for DHEA in the prevention of fat deposition in poultry.
Supplemental zinc reduced intestinal permeability by enhancing occludin and zonula occludens protein-1 (ZO-1) expression in weaning piglets
Authors: Zhang Bingkun , Guo Yuming
Published: March 2009

The present study was carried out to evaluate the pharmacological effect of Zn in diarrhoea in relation to intestinal permeability. Seventy-two weaning piglets, aged 24 d, were allocated to three dietary treatments: (1) control diet without supplemental Zn; (2) control diet supplemented with 2000 mg Zn/kg from ZnO; (3) control diet supplemented with 2000 mg Zn/kg from tetrabasic zinc chloride (TBZC). At the end of a 14 d experiment period, piglets were weighed, feed consumption was measured, and mucosal barrier function was determined using the lactulose/mannitol test. Expression of mucosal tight junction protein was measured at RNA and protein level. Inclusion of TBZC or ZnO in the diet significantly increased average daily gain (P < 0·01) and average daily feed intake (P < 0·05), while leading to reduced feed conversion ratio (P < 0·05) and faecal scores (P < 0·01). TBZC reduced urinary lactulose:mannitol ratios of weaning piglets (P < 0·05), while dietary supplementation with ZnO tended to reduce urinary lactulose:mannitol ratios (P = 0·061). ZnO or TBZC significantly enhanced the mRNA and protein expression of occludin (P < 0·05) and zonula occludens protein-1 (ZO-1) (P < 0·05) in the ileal mucosa. Piglets fed the TBZC-supplemented diet had a higher level of occludin than pigs fed the ZnO-supplemented diet (P < 0·05). The results indicate that Zn supplementation decreased faecal scores and the reduction was accompanied by reduced intestinal permeability, which was evident from the reduced urinary lactulose:mannitol ratios and increased expression of occludin and ZO-1. Therefore, the protective effect of pharmacological levels of dietary Zn in reducing diarrhoea might, at least partly, be associated with reduced intestinal permeability.
State and Religion in Athenian Inscriptions
Authors: RHODES P. J.
Published: March 2009

In our present-day secular society, which regards religion as an optional extra for those who like that sort of thing, it is trumpeted as a great discovery that, in classical Greece, religion was not an optional extra detached from the rest of society's working but was ‘embedded’ in the various workings of society. It is of course our society that is exceptional: religion has been embedded in most societies through most of human history. Christianity was far more effectively embedded in western societies in the past than it is now; there are still some links in England between the Church of England and the state, and there are rather stronger links in Norway between the Lutheran church and the state; some Christian festivals are still widely observed as public holidays; and, in other parts of the world (for instance, many countries in which Islam is the predominant religion), the links between religion and state are still much stronger.
Dinner at Seneca's Table: The Philosophy of Food
Authors: RICHARDSON-HAY CHRISTINE
Published: March 2009

There is an abundance ‘to eat’ in the pages of Roman literature, where lavish and exotic dishes crowd the tables at banquets that flatter and fortify indulgent and insatiable appetites in unrestrained festivals of eating and drinking. As Emily Gowers explains, ‘Imperium had turned Rome into the world's emporium: its alimentary choices are presented as almost infinite, from the turnips of Romulus to the larks' tongues of Elagabalus’. Nevertheless, in Roman society, where the food a person ate (its quality, quantity, and presentation) reflected their station in life and where large numbers of the population struggled at subsistence levels, these literary banquets are neither reliable, nor even factual, accounts of a Roman meal. In fact, food or events of consumption appear to have occupied an ambivalent, even undistinguished, place in Roman literature, which typically saw their inclusion in comedy, satire, epigram, and the epistle but not the serious genres of epic, tragedy, elegy, or lyric. Generic considerations could possibly therefore influence an author's inclusion of culinary description in ancient literature, although food details did not merely satisfy these expectations and were typically shaped by the attitudes, social values, or artistic insights of an individual author.
Electrostatic fields and charged particle acceleration in laser produced plasmas
Authors: Hora Heinrich
Published: March 2009

While the action of electrostatic double layers in the periphery of an expanding laser produced plasma has been discussed and treated many years ago, some new aspects pioneered recently by Alfvén in the theory of cosmic plasmas, indicate the possibility of a new treatment. The thermally produced electrostatic double layer which has been re-derived for a homogeneous plasma shows that a strong upshift of ion energies (by the mass ratio) is possible, in agreement with experiments. The number of accelerated ions is many orders of magnitude smaller than observed at keV and MeV energies. The nonlinear force acceleration could explain the number and energy of the observed fast ions. It is shown, however, that electrostatic double layers can be generated which should produce super-fast ions. This paper presents a derivation of the spread double layers in the case of inhomogeneous plasmas. It is concluded that the hydrodynamically expected multi GeV heavy ions for 10TW laser pulses (generated by relativistic self-focussing and nonlinear forces) should produce super-fast ions up to the TeV range. Further conclusions are drawn from the electrostatically measured upshifted (by 300 keV) DT fusion alphas from laser compressed plasma. An analysis of alpha spectra attempts to distinguish between different models of the stopping power in the plasmas. The analysis preliminarily arrives at a preference for the collective model.
Two-dimensional ion emission from laser-produced plasmas
Authors: Tallents G. J.
Published: March 2009

The expansion of laser-produced plasmas in two-dimensions is examined analytically using an asymptotic (time→∞) isothermal self-similar model. The ion emission velocity and energy spectra are calculated and expressions given for the number and energy of expanding ions as a function of angle to the target. By relating the total ion kinetic energy of expansion to the temperature of the initial plasma, it is shown that ion probe signals give a measure of the initial plasma temperature. The model is extended to a plasma with two initial temperatures (a ‘hot’ component and a ‘cold’ component) and it is shown that the ion energy spectra here can be used to deduce the initial temperatures of the ‘hot’ and ‘cold’ ions and the relative number of the ‘hot’ ions to the ‘cold’ ions. The results are used to interpret data from an array of ion probes (at different angles to the target) for a plasma produced by irradiating a 25 μm thick nickel foil with a ∼20 ρs neodymium laser pulse.
Field emission cathode for high power beams
Authors: Petr Rodney , Gundersen Martin
Published: March 2009

Field emission is identified as the mechanism responsible for high current emission (50 A/cm2 at 300°K) from a dispenser-type cathode. This cathode has advantages for high power operation, and should be suitable for practical applications.
Self-consistent calculations of short-pulse laser-heated plasma dynamics
Authors: Lädrach P. , Balmer J. E.
Published: March 2009

A one-dimensional, time-dependent fluid code is presented that numerically solves the hydrodynamic equations together with the wave equation for a picosecond pulse laser heated plasma. The laser light absorption by classical inverse bremsstrahlung and the ponderomotive force are evaluated self-consistently from the computed electromagnetic field quantities. At oblique incidence of p-polarized 1·054 μm laser radiation the resonant electric field is saturated by plasma wave convection through the nonlinear density profile steepening prior to wave breaking.
Computer modelling of e-beam-pumped KrF lasers
Authors: Edwards C. B. , O'Neill F.
Published: March 2009

A computer kinetics model has been developed to predict the steady state behaviour of e-beam-pumped KrF lasers. The model can be used to calculate species densities, gain, loss and laser efficiency. Close agreement is obtained between the model predictions and a wide range of experimental measurements of optical gain, loss, and laser efficiency as a function of e-beam pump power, taken at various laboratories.
Determination of atomic cross-sections for electron impact excitation using effective Feynman diagrams and Einstein coefficients
Authors: Eliezer Shalom , Salzmann David
Published: March 2009

An ‘effective Feynman diagram’ technique is introduced to obtain relations between the cross-sections of various atomic processes. In this paper the technique is used to obtain a simple relation between the cross-sections of electron impact excitation and resonant photon absorption. The method is important because calculations of complicated atomic wavefunctions are eliminated.
Double layer (DL) formation in laser-produced plasma
Authors: Eliezer Shalom , Ludmirsky Ariold
Published: March 2009

It is shown that appropriate conditions for DL formation may be created in laser produced plasma. In particular, a ‘feedback’ mechanism is suggested:

Wave instabilities → absorption of laser energy → inward heat flux → DL formation → heat flux inhibition → wave instabilities

Plasma-target potentials and plasma-currents, produced by Nd. laser intensities (IL) between 1012 to 1015 W/cm2, were measured in situ. These measurements seem to be the first direct evidence of DLs in laser produced plasma. Electric fields of EDL ∼ 5 × 105 to 5 × 106 Volts/cm and widths of 10 to 100 Debye lengths are estimated for the DL.

Scaling laws are derived for the measured extremum potentials (V) and currents (I): . Two different slopes were obtained experimentally, one slope equal to α = β = 1·0 for IL < 1014 W/cm2 and another of α = β = 0·4 for IL > 1014 W/cm2. These data are explained for temperature scaling law for the low irradiance and for the high irradiance. While the first scaling law is consistent with inverse bremsstrahlung absorption, the second scaling necessitates other absorption processes. Potential and current probes are suggested as useful devices in detecting wave plasma instabilities.
A laser plasma interaction model for the conditions of stimulated Brillouin backscattering model experiments
Authors: Handke J. , Rizvi S. A. H. , Kronast B.
Published: March 2009

A model of laser interaction with a preformed target plasma is developed for the conditions of so called stimulated Brillouin backscattering (SBS) model experiments and its applicability is demonstrated by various tests. Most of the features can be understood from analytical approximations. A consequence of irradiation by a narrow beam, typical of model experiments, is the stabilization of electron temperature at low values. Another consequence equally unexpected is the SBS threshold dependence on beam radius and the particular power law dependence on plasma density. On the basis of this model the wide scatter of the SBS threshold between model experiments can be explained. It is also demonstrated that, for the conditions of these model experiments, classical Spitzer heat conduction suffices.
Instabilities of bounded plane plasma irradiated by a high intensity laser beam
Authors: Runwen Wang
Published: March 2009

Starting from two-wave coupled plasma equations the parametric decay instabilities appearing in homogeneous plasmas are discussed as a first step. If damping is present, the instabilities may appear, and when the damping is so small that it can be neglected, there exists only spatial gain. The analytic solution for inhomogeneous plasma, as a second step, with density varying almost linearly is obtained and the conditions for the instabilities to occur are discussed.
Irradiation symmetry of heavy ion driven inertial confinement fusion (ICF) targets
Authors: Buchwald G. , Graebner G. , Theis J. , Maruhn J. A. , Stöcker H. , Kruse H.
Published: March 2009

The symmetry of heavy ion driven inertial confinement fusion targets is investigated with a two-dimensional Eulerian hydrodynamic code. The importance of the beam geometry is studied. The HIBALL design in its present form seems to inhibit a spherical implosion of the target. It is shown that the beam angle in the HIBALL geometry should be about 35 degrees.
Excitation of large amplitude electron plasma waves by laser
Authors: Mulser P. , Schnabl H.
Published: March 2009

A hydrodynamic description is used to derive a nonlinear wave equation in the geometry of the capacitor model. For a streaming cold plasma the equation can be solved analytically. For the warm plasma case numerical results of high amplitude waves and wave breaking are presented. Flat minima and peaked maxima of the electron density and the oscillatory velocity are the most characteristic features of highly nonlinear electron waves. Their Bohm–Gross dispersion relation is modified by self-interaction of the fundamental mode.
A new maser effect in plasma turbulence
Authors: Nambu M.
Published: March 2009

The present state of understanding of a new maser effect is reviewed. The new maser effect, the idea that the resonant electrons in a turbulent plasma can radiate amplified electromagnetic radiation, does not require population inversion of electrons. The new maser effect always coexists with Landau (or cyclotron) damping; thus it is a fundamental effect in plasma turbulence. In nuclear fusion, magnetic confinement will be at a disadvantage due to the enhanced radiation losses in the long wave length region, while inertial confinement will be improved by the laser effect in the X-ray region
Laser produced plasma as an ion source for heavy ion inertial fusion
Authors: Barabash L. Z. , Koshkarev D. G. , Lapitskii Yu. I. , Latyshev S. V. , Shumshurov A. V. , Bykovskii Yu. A. , Golvbev A. A. , Kosyrev Yu. P. , Krechet K. I. , Haydarov R. T. , Sharkov B. Yu.
Published: March 2009

The present paper presents experimental results of the transverse and longitudinal phase volume for the expanding multicharged ions in laser produced plasma, created by focusing a CO2-laser (beam) onto a Pb207 target. The total number of Pb207 ions (with Z = 1 or 2 and Z = 6), the ion current duration and amplitude at a distance of 1 m from the laser target within 10−2 steradians are determined. The measured experimental parameters of the laser heavy ion source are compared with the driver requirement for the heavy ion inertial fusion (HIIF) programme.

The phenomena observed in the experiment confirm the results of numerical calculations using a two temperature hydrodynamic programme.
The investigation of heating and compression of high-aspect ratio targets with ‘Delfin-1’
Authors: Basov N. G. , Danilov A. E. , Kalashnikov M. P. , Kruglov B. V. , Mikhailov Yu A. , Rode A. V. , Sklizkov G. V. , Fedotov S. I.
Published: March 2009

Experimental results on the compression of shell targets with aspect ratio A = 150–250 in the “Delfin-1” installation are reported. The absorbed laser energy was 0·3 to 0·5 kJ. The maximum compression was 3·5 × 103, the velocity of target compression at the final stage was 2·6 × 107 cm/s, neutron yield was 106 to 107 D-D neutrons per laser shot. The appearence of plasma corona filamentation correlated with compression stability distruction.
Comments on “A simple model of ion beam heated ICF targets” by R. G. Evans
Authors: Ahlborn Boye
Published: March 2009

In a recent study R. G. Evans developed an analytic model for ICF targets heated by heavy ion beams in order to show the differences to laser beam heating. However, these differences are really not very pronounced. In fact, Evans' model should be directly applicable to describe exploding pusher foil targets. In addition, Evans' scaling law for the ablation pressure PA with target density ρ0 and particle beam intensity Ib,

is identical to the scaling found for laser targets with tamped flow (Ahlborn, 1981).
A fundamental theory of high power thyratrons for high power laser and beam applications III: the production of radiation
Authors: Kunc J. A. , Shemansky D. E. , Gundersen M. A.
Published: March 2009

The radiation characteristics of a high-current hydrogen thyratron plasma have been modeled in order to study this aspect of the physics of the conductive phase of thyratron operation. The intensities and radiative energy efficiencies of the atomic and molecular systems have been calculated in detail. A model is developed that is useful for studies of photoemission. For discharge parameters Te ≈ 1 eV, ionization fraction of ∼10−2 and background density of 1016 cm−3, the total power of the emitted radiation is estimated to be of the order of 5% of the total input power during the conductive phase.
A new nonheated copper vapor laser
Authors: Ludmirsky Ariold
Published: March 2009

A new method for decreasing the operating temperature of copper vapor lasers (CVL) by pulsed injection of pure metal vapor into the active volume of the laser is described. The inductively produced copper plasma is accelerated by a pulsed magnetic field. As a result the laser operates at room temperature in a double-pulse mode. The population densities of both the ground and metastable states of copper atoms were derived from optical absorption measurements. The metastable level density decays rapidly while the ground-state densities exist up to 2 msec without noticeable changes. The scaling of this type of laser was studied. A 24 mJ output laser pulse of 65 ns duration was obtained for a laser tube 90 cm long and 10 cm bore. The advantages of the new CVL are discussed.
Hybrid ion diode experiment on PBFA I
Authors: Miller P. A. , Dreike P. L. , Quintenz J. P. , Anderson R. J. , Crow J. T. , Mendel C. W. , Mills G. S. , Mix L. P. , Rosenthal S. E. , Seidel D. B. , Vandevender J. P.
Published: March 2009

The development of high power ion diodes for inertial confinement fusion is in progress on the PBFA I accelerator. The three main types of magnetically-insulated ion diodes, the Applied-B, Hybrid, and Pinch Reflex diodes, are compared. This paper presents the results from the first series of tests of the Hybrid diode.
Charged particle spectra from U-235 and B-10 micropellets and slab coatings
Authors: Chung A. K. , Prelas M. A.
Published: March 2009

A novel method of utilizing fluorescence generated from the products of nuclear reactions offers the prospect of compact, high efficiency, multi-megajoule lasers. To overcome the problems associated with traditional laser (or energy converter)-fissile material interfaces, such as a uranium coating (low power density and low efficiency) or a gaseous uranium compound (low power density and deleterious effects on the laser kinetics and photon transport), a method suggested elsewhere of employing a reactor using a uranium aerosol fuel, interspersed with a fluorescer medium, is briefly reviewed. The charged particles produced by nuclear reactions in the fuel produce fluorescence in the core region of the reactor, through interactions with the fluorescer. This fluorescence can then be concentrated, to increase the effective power density in the laser medium, and used to drive a photolytic laser.

One key issue in the above process is the charged particle spectrum from the fissile aerosol. These issues can be addressed theoretically based on the Dirac chord length distribution technique and an Arcen's function. The charged particle spectrum from a UO2 coating has been generated and benchmarked with the experimental data of Kahn et al., and Redmond et al. Agreement is generally good except near the end of the fission fragment tracks. The validity of this simple technique in approximating the rate of ion energy loss lends confidence to the generation of fission fragment spectra for other geometries (i.e. spherical in which transport efficiencies of over 60% appear achievable) using U, UO2 and U3O8. Work is also extended to the case of B-10 in a variety of configurations which are frequently used in modern energy conversion experimental devices.
On absorption of the laser radiation in a plasma with subcritical density
Authors: Alexandrov V. V. , Kovalsky N. G. , Pergament M. I. , Rubenchik A. M.
Published: March 2009

Absorption, reflection and scattering of laser radiation have been studied in experiments with oblique incidence of Nd glass laser beams on plane massive targets of polyethylene, aluminium and copper. Time behaviour of 2ω and 3/2;ω harmonic intensities and their angular distributions were measured along with plasma X-ray spectra in the flux density range 1013 to 3×1014 W/cm2 for 3.5 nsec laser pulses. Comparison of the experimental data with the results of the theoretical analysis and numerical calculations is presented and relatively strong absorption of about 10% is estimated in the quarter critical density region of the plasma corona due to the two-plasmon decay instability growth. The hard X-ray component in the X-ray spectrum disappears at large angles of incidence, hence the supra-thermal electron generation and two-plasmon instability are proven to be coupled phenomena.
Ion beam divergence due to plasma heating in the Ampfion diode
Authors: Olson Craig L.
Published: March 2009

In the Ampfion diode, an ion beam is extracted from an anode plasma that is being pushed away from the cathode by a rising magnetic field. There is concern that ion heating in the anode plasma sheath may result in a significant ion beam divergence. To investigate this possibility, a comparison of Z pinches, θ pinches, and Ampfion is made. Ampfion sheath scenarios are examined and a simple argument is presented that indicates that an anomalous resistivity should develop. An upper bound estimate of the ion divergence is calculated, and examples are given for PBFA-II parameters. For a small radius diode with a high density anode plasma, it is shown that ion beam divergence due to plasma heating should not be a problem. For a large radius diode with a low density anode plasma, it is shown that ion beam divergence due to plasma heating is a problem, but that an Ampfion filtering mechanism should select a cool portion of the heated ions and help to alleviate this problem.
Ponderomotive force of a high-frequency electromagnetic field in a dispersive plasma
Authors: Vuković S.
Published: March 2009

Ponderomotive force density of an HF field in a dispersive cold collisionless plasma is calculated using two independent methods: energy-momentum-stress tensor with the Abraham choice of momentum density and two-fluid hydrodynamics. The results appear to coincide and show that, even in isotropic plasma, terms proportional to the time derivative of the electric field amplitude appear in the ponderomotive force. It is demonstrated that, in the presence of relativistic electron beams, spatial dispersion is not negligible and the related correction to the ponderomotive force is calculated.
A simple model for soft X-ray conversion efficiency from laser-irradiated gold disk targets
Authors: Lee P. H. Y. , Ahlstrom H. G.
Published: March 2009

Simple arguments are used to construct a model to explain the conversion efficiency of absorbed laser energy into soft X-rays from laser-irradiated targets. In this model, we postulate that the energy available for conversion is bounded at some low irradiance limit by heat conduction away from the laser heated spot, while at some high irradiance limit it is bounded by the energy lost in plasma blowoff. Consequently, at some appropriate laser intensity, where the sum energy of the conduction and blowoff losses is at a minimum, the X-ray conversion efficiency should reach a maximum. A specific example for gold disk targets irradiated by 0·53 μm laser light will be treated. Simple heuristic scalings of blowoff and conduction as functions of laser intensity are obtained.
Recent theoretical and experimental results of high-current transport studies
Authors: Reiser M.
Published: March 2009

In this paper recent simulation studies at GSI on instabilities and emittance growth for different particle distributions and initial experimental results with the 12-lens section of the University of Maryland electron beam transport channel are reviewed.
Inertial Confinement Fusion in Japan
Authors: Yamanaka Chiyoe
Published: March 2009

The facilities and activities of inertial confinement fusion research in Japan are reviewed. The key institute is ILE Osaka University where the implosion scheme of the “Cannonball Target” has been investigated in experiments and computer simulations to overcome the critical issues in inertial confinement fusion.
Atomic physics for beam-target interactions
Authors: Deutsch C.
Published: March 2009

This survey is devoted to a few basic atomic problems associated with the stopping of nonrelativistic pointlike ions in dense and hot matter, and also to the Stark broadening diagnostics of the resulting beam-produced plasmas.

First, we consider the free electron contribution, taken in the RPA approximation with an exact dynamic dielectric function, valid at any temperature. Therefore, we obtain stopping power and straggling for any projectile velocity. The temperature dependence is of special relevance for a projectile energy smaller than 5 MeV/a.m.u.

Next, we revise the Barkas effect (Z3 corrections) through a novel and compact formulation, which is based on an analogy with electron impact broadening theory. It facilitates inclusion of the non hydrogenic and electronic structure of the target ions, in a more selective way. The results may increase the usual Z2-stopping by 15 to 30 per cent corrections.

Then, we show how the Stark broadening diagnostics of the compressed D + T fuel, seeded with high Z species, arising from the surrounding envelopes, may provide accurate determination of the electron number density ne. In this connection, it should be appreciated that the relatively long compression times (≃ 20 nsec) suggested by the HIBALL numerical simulation allow for a nearly Local Thermodynamic Equilibrium (LTE) state in the target, with Te ≃ Ti. As a consequence, spectroscopic measurements are expected to be easier to implement in HIF targets, than in laser ones.

A tentative proposal for the use of Stark broadening diagnostics of inflight excited and highly stripped ion projectiles is displayed in § 5.

Experiments involving an HIB produced by a standard accelerator, and interacting with an independently produced coronal plasma are finally outlined.
Charge equilibrium of fast heavy ions traversing through gaseous media
Authors: Karashima S. , Watanabe T.
Published: March 2009

The charge distribution of an incident ion as a function of projectile velocity, its range and its average equilibrium charge are studied theoretically. The calculations are made only for an atomic hydrogen gas target. The charge of the ion is determined by the equilibrium between electron loss from the ion and electron capature from a hydrogen atom to the ion. The charge states of the ions are calculated in two cases; to assume a local balance condition for electron loss and capture and to solve a rate equation for the charge state fraction function under non-local balance conditions, both only taking into account single electron loss and capture processes. In the calculations we use empirical formulae for electron loss and capture cross section by making some simplifications. Calculations for the charge state fraction as functions of ion ranges under non-equilibrium conditions have been carried out in the cases of Ne, Ar, and Xe ions. Calculations for the charge state under local balance conditions have been made in the cases of C, Ne, Ar, Kr, I, and U ions.
Exploration of fusion conditions in radio frequency discharge cavitons
Authors: Handel P. H.
Published: March 2009

The experimental generation of fusion neutrons in low power and voltage deuterium RF discharges with plasma solitons is analyzed here on the basis of recently derived high internal electric fields present in non-uniform plasmas. Ion oscillation energies of 10 keV are derived and provide an explanation of the observed neutron generation rate of 105 per second.
A comparison of recombination and photo-pumping mechanisms for producing hydrogen-like Balmer alpha gain
Authors: Tallents G. J.
Published: March 2009

A comparison of the recombination and photo-pumping approaches for producing X-ray lasing on the hydrogen-like Balmer alpha line is presented. An approximate analytic expression for the ratio of the populations of the n = 3 and 2 quantum states of the hydrogen-like ion is derived and used to delineate the plasma parameter space where Balmer alpha gain can occur in a recombining plasma. The photo-pumping intensities required to produce Balmer alpha gain for plasmas initially in the steadystate are calculated using a collisional-radiative code and compared to intensities required to produce the initial plasmas for a recombination Balmer alpha laser with comparable gain. The recombination approach becomes relatively more efficient compared to the photo-pumping approach with increasing atomic number Z of the hydrogen-like ion with an estimated break-even at approximately Z = 16.
Design study of a heavy ion fusion driver, HIBLIC
Authors: Katayama T. , Itano A. , Noda A. , Takanaka M. , Yamada S. , Hirao Y.
Published: March 2009

A heavy ion fusion (HIF) system, named HIBLIC (Heavy Ion Beam and LIthium Curtain) is conceptually designed. The driver system consists of RF linacs (RFQ linacs, IH linacs and Alvarez linacs), storage rings (one accumulator ring and three buncher rings) and beam transport lines with induction beam compressors. This accelerator complex provides 6 beams of 15 GeV208Pb1+ ions to be focused simultaneously on a target. Each beam carries 1·78 kA current with 25 ns pulse duration, i.e., the total incident energy on the target is 4 MJ, 160 TW per shot. Superconducting coils are used in most parts of the magnet system to reduce power consumption.