210 research outputs found
Radio Echo-Sounding Of Shirase Glacier And The Yamato Mountains Area
No full textIn 1979, the National Institute of Polar Research (NIPR) developed a 179 MHz airborne radio echo-sounder (NIPR-A), and installed it in a Pilatus Porter PC-6 aircraft. The peak power of the sounder is about lkW and the pulse width is 0.3 ys. Soundings were carried out in Antarctica on Shirase Glacier and the Yamato Mountains in January 1980. The total flight distance over the Shirase Glacier was about 500 km in six flights, while, on the Yamato Mountains area, about 80 km long, two north-south flights and three eastwest flights were carried out.
In spite of poor wave penetration, the presence of many sub-glacial uplands (1 000 to 2 000 m a.s.l.) near the Yamato Mountains area was revealed. Discussion is concentrated on the bedrock and surface topography of the bare ice area near Motoi Nunatak in the southeast Yamato Mountains, because the previous traverse party covered this area and many meteorites have been discovered here.
A high sub-ice ridge with three peaks extends east of Motoi Nunatak, and from 22 to 28 km east of Motoi Nunatak there is a short ridge with two peaks. From 12 to 20 km up-glacier from Motoi Nunatak, a long but comparatively low ridge surrounds Motoi Nunatak ridge like an arc. Finally, the sub-ice flow lines near Motoi Nunatak are deduced from new and earlier data.</jats:p
Radio Echo-Sounding Of Shirase Glacier And The Yamato Mountains Area
No full textIn 1979, the National Institute of Polar Research (NIPR) developed a 179 MHz airborne radio echo-sounder (NIPR-A), and installed it in a Pilatus Porter PC-6 aircraft. The peak power of the sounder is about lkW and the pulse width is 0.3 ys. Soundings were carried out in Antarctica on Shirase Glacier and the Yamato Mountains in January 1980. The total flight distance over the Shirase Glacier was about 500 km in six flights, while, on the Yamato Mountains area, about 80 km long, two north-south flights and three eastwest flights were carried out.In spite of poor wave penetration, the presence of many sub-glacial uplands (1 000 to 2 000 m a.s.l.) near the Yamato Mountains area was revealed. Discussion is concentrated on the bedrock and surface topography of the bare ice area near Motoi Nunatak in the southeast Yamato Mountains, because the previous traverse party covered this area and many meteorites have been discovered here.A high sub-ice ridge with three peaks extends east of Motoi Nunatak, and from 22 to 28 km east of Motoi Nunatak there is a short ridge with two peaks. From 12 to 20 km up-glacier from Motoi Nunatak, a long but comparatively low ridge surrounds Motoi Nunatak ridge like an arc. Finally, the sub-ice flow lines near Motoi Nunatak are deduced from new and earlier data.</jats:p
Spectroscopic study of molecular hydrogen concentration at the vicinity of metal surfaces
No full textHighlight misconceptions in Physics: a T.I.M.E. project
No full textSince the early 1970s it has been pointed out that many higher education students have a fairly large number of mistaken ideas on some Physics topics. Indeed, the term “misconceptions” was introduced for the first time in 1972. This theme is worthy of investigation in order to improve the students’ outcomes in basic Physics courses and to tackle the issue of the growing number of dropouts. Consisting of three main stages closely connected with each other, our research aims at identifying, comparing and overcoming the most significant and widespread misconceptions shown by first-year university students enrolled for engineering, in relation to their basic knowledge of Physics, with specific reference to Mechanics, Thermodynamics and Electromagnetism. It is being developed by Politecnico di Milano [ITA] along with Doshisha University [JAP] and Bauman Moscow State Technical University [RUS], which offer Physics and Engineering courses, as well as with Università degli Studi di Trento [ITA], which provides pedagogic support. First of all, data about the above mentioned misconceptions were gathered by each technical institution through the use of an ad hoc test, which consisted of 12 multiple choice quizzes administered to about 750 students attending the 7 courses globally involved in the research. Hence, misconceptions related to the main macro-areas were further classified according to specific headings, i.e. kinematics, heat engine, electric field, among others. Secondly, the misconceptions expressed by the students attending the different universities involved in the research were compared. They appear to be broadly widespread among the freshmen, with Electromagnetism being the macro-area where the students’ results are the worst. Throughout the third and final stage of our study, a trial video has been produced to enable students to overcome some significant misconceptions
Photo-assisted O− and Al− production with a cesium sputter ion source
No full textIt has been recently proposed that the production of negative ions with cesium sputter ion sources could be enhanced by laser-assisted resonant ion pair production. We have tested this hypothesis by measuring the effect of pulsed diode lasers at various wavelengths on the O− and Al− beam current produced from Al2O3 cathode of a cesium sputter ion source. The experimental results provide evidence for the existence of a wavelength-dependent photo-assisted enhancement of negative ion currents but cast doubt on its alleged resonant nature as the effect is observed for both O− and Al− ions at laser energies above a certain threshold. The beam current transients observed during the laser pulses suggest that the magnitude and longevity of the beam current enhancement depends on the cesium balance on the cathode surface. It is shown that the ions produced by the laser exposure originate from slightly different potential than the surface produced ions, which allows us to constrain the underlying physical mechanisms. It is concluded that the photo-assisted negative ion production could be of practical importance as it can more than double the extracted beam current under certain operational settings of the cesium sputter ion source. We discuss experiments designed to confirm or dispute the relevance of the ion pair production for negative ion production with cesium sputter ion sources and the possibility of ion pair production explaining the beneficial effect of xenon admixture on the negative ion yield of an RF-driven H− ion source.peerReviewe
Pressure dependence of current-voltage characteristics of a thin hole hollow cathode
No full textチタニア(TiO2)ナノ構造がプラズマに基づいた合成過程により実現可能である．真空装置への複雑なチタニア粉末の導入に基づいた生成過程ではなく，純粋チタン陰極からの直接スパッター法により，TiO2薄膜を形成する方法も有効と考えられる．12mm長，0.7mm系の細孔を有する直径12mmのチタン電極を用いて，圧力10から100Paのアルゴン雰囲気化で安定に放電形成することができた．薄膜形成系に本電極を挿入することによって得られる粒子フラックスを評価し，また装置の運転状態を，薄膜堆積ターゲットを模した電極を挿入して電流電圧特性を得ることによってモニターすることの有効性について調査した．A Ti hollow cathode electrode with a 0.7 mm aperture was designed to examine its performance in Ar discharge production and its potential as a sputter source for the formation of TiO2. The electrode demonstrated excellent stability against high-voltage break down and was able to sustain Ar discharge in the pressure range from 10 to 100 Pa. The steady state production of metallic particle flux is expected with enough cathode voltage to ensure a necessary sputtering yield. The source can generate the sputtered atom flux of the order of one monolayer per second and can serve as the Ti source for TiO2 atomic layer film preparation.原著論文This work was supported in part by grants-in-aid for division research from the Harris Science Research Institute of Doshisha University.departmental bulletin pape
Preface: Special issue for “The First International Symposium of the Vacuum Society of the Philippines”
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