Von Ardenne Research Articles

Ergebnisse der Sauerstoff-Mehrschritt-Therapie bei der Behandlung des Hörsturzes

Oxygen multistep therapy (von Ardenne) was applied in 28 patients suffering from an idiopathic sudden hearing loss. The oxygen therapy consisted of a multistep short procedure, each of which lasted for 15 minutes. The results of our study were evaluated by means of standardised statistics confirming the effectiveness and even the superiority of the oxygen multistep therapy in comparison with any other treatment, and also in view of the spontaneous remission rate in cases of sudden hearing loss.

Image formation in the scanning electron microscope

Image formation in the scanning electron microscope (SEM) was discussed in theory by von Ardenne. It was reduced to practice by von Ardenne, Knoll, McMullan, Smith and Oatley and Smith. The basic ideas are as follows. An electron beam (EB) of diameter dEBis scanned over a solid specimen. This penetrates for a distance dPENbelow the surface. A signal is collected and modulates the brightness of a cathode ray tube scanned in sympathy with the EB. While the resolution is always limited by dEB, it is not always limited by dPEN.Secondary electron (SE) imaging. von Ardenne distinguished between the secondary electrons (SE) with an energy lower than 50 eV and the backscattered electrons (BSE) having energies between 50 eV and the primary energy E0. He proposed that SE that escape at the point of entry of the EB (now called SE-I) should provide a high resolution component to the SE image, while SE excited at the exit point (now called SE-II) escape from a larger area and so give rise to an image with a poorer resolution. (Also see Peters.6)

German Television pioneers and the conflict between Public Programming and Wonder Weapons

This article illuminates the position from which researchers in East Germany on the history of television have reconstructed the early development of German television [1]. It focuses on the struggle of television's pioneers for a progressive, socially conscious use of this audio-visual broadcast medium, and on their stand for the preservation and restoration of peace. In this portrayal, figures such as Ardenne, Bronnen, Dressler-Andress, Hatschek, Karolus, Kruckow, Loewe and many others, as well as those who worked against them, are seen in a new light. This treatment of the topic is based on primary sources located and preserved in archives of the German Democratic Republic (GDR). Among these is photographic material of the Reich's broadcasting companies (Reichs-Rundfunk-Gesellschaft and the Reichssender Deutscher Fernseh-Rundfunk), files of the Reich's security agency and of the National Socialist's Supreme Court, as well as series of documents of the Reichspostministerium and the Reichsministerium für Volksaufklärung und Propaganda (Ministry of Post and the Ministry of People's Information and Propaganda of the German Reich) published by the author over the past 20 years. Also deserving mention are the estates of Ernst Augustin and Horst Dressler-Andress, as well as records on the memories of contributors to the early development of German television who live in the GDR, such as Professor Dr h. c. mult. Manfred von Ardenne.

Making every electron count: Detectors for scanning electron microscopy

Fifty years ago, in December 1937, Manfred von Ardenne submitted his first paper on the scanning electron microscope (SEM) to Zeitschrift für Physik. Moreover his eightieth birthday was on January 20th this year and it is therefore now very appropriate that we should remember the great contribution he made to the subject by that mainly theoretical paper and by the one he published a few months later on the practical realisation of the first scanning transmission electron microscope (STEM); both papers have been frequently cited in the literature. Von Ardenne designed a two-lens microscope and calculated the current in a 10nm focussed spot to be 10-12A; he also discussed how the detector should be arranged to give bright and dark field images from a transparent specimen and secondary electron images from a solid specimen. Unfortunately, at that time the only device available to him for amplifying such small currents was the thermionic valve and he quickly realised that the noise level would be much too high.

The early history of the scanning electron microscope

The article begins with an account of prewar German work, particularly that of von Ardenne, who established the theoretical basis of a scanning electron microscope and constructed an instrument which was primarily intended to overcome chromatic aberration when relatively thick specimens were examined by transmission. Neither this microscope nor a different one built a few years later in the U. S. A. attained sufficient resolution to gain acceptance and the reasons for this are examined. The remainder of the article deals with work carried out in the Cambridge University Engineering Department over the years from 1948 to about 1965, when the first successful commercial instrument was produced. The contributions made by successive research students are explained, as are also the nonscientific factors which influenced the course of the development.

Massenspektroskopische Untersuchungen von 5‐halogenierten Pyrimidinglucuroniden

Mass Spectroscopy of 5‐Halogenated PyrimidinglucuronidesUsing the ion source according to von ARDENNE, useful spectra of negative and positive ions from sensitive glycosides were obtained either by electron attachment (EA‐) or low voltage electron impact (EI‐) mass spectroscopy.Spectra of glucuronides derived from 5‐halogenated uracil, 2‐thiouracil, 4‐thiouracil and 6‐mercaptopurin in their peracetylated, esterified and free acidic form are described. Most stable peracetylated 2‐ and 4‐thiouracil glucuronides reveal intensive peaks of molecule ions.The halogen‐carbon bonding strength, calculated from complementary aglycon peaks, demonstrates expected tendencies due to the halogen.

Mass Spectrometry of Negative Ions

Abstract“It appears that negative ion mass spectra measured with a commercial instrument and the electron energies used (20–70 eV) are not suitable either for molecular weight or for structure determination—”. This was the conclusion of a paper appearing in 1965 which expressed the then almost universal opinion on the importance of negative ion mass spectrometry in the structure analysis of organic compounds[8]. The fact that quinones and aromatic nitro compounds were exceptions to this rule was rather taken as substantiation of this opinion. The potential value of the work originating from the laboratories of Manfred von Ardenne was first realized with the development of chemical ionization. This technique gave a firm foundation to negative ion spectrometry in the area where it is complementary to that of positive ions.

Stereo imaging in the shadow electron microscope

Stereo imaging is not new to electron microscopy. Von Ardenne, who first published transmission pairs nearly forty hears ago, himself refers to a patent application by Ruska in 1934. In the early days of the electron microscope von Ardenne employed a pair of magnetic lenses to view untilted specimens but soon opted for the now standard technique of tilting the specimen with respect to the beam.In the shadow electron microscope stereo images can, of course, be obtained by tilting the specimen between micrographs. This obvious method suffers from the disadvantage that the magnification is very sensitive to small changes in specimen height which accompany tilting in the less sophisticated stages and it is also time consuming. A more convenient method is provided by horizontally displacing the specimen between micrographs. The specimen is not tilted and the technique is both simple and rapid, stereo pairs being obtained in less than thirty seconds.

Negative ion mass spectrometry of the new riboflavin metabolite: 7,8‐dimethyl‐10‐formylmethyl‐isoalloxazine ethyl‐hemi‐alcoholate (flavin‐10‐acetaldehyde ethyl‐hemi‐alcoholate)

AbstractFlavin‐10‐acetaldehyde ethyl hemi‐alcoholate obtained at the Hannah Dairy Research Institute by bacterial degradation of riboflavin was examined in the Electron Attachment (EA) apparatus at the Forschungsinstitut Manfred von Ardenne. At low temperatures pyrolysis was negligible and the peak of greatest mass was only four units less than the molecular weight. The fragmentation patterns at greater field strengths indicated metastable peaks of masses in accord with the fragmentation pattern at lower fields. The patterns at the lower temperatures used resembled in important respects the EA pattern from riboflavin in an earlier study. In explanation of the fragmentation pattern obtained, structures have been assigned to the ions recorded.

The Injector Complex for the LAMPF Accelerator

The present planning and design goals for the LAMPF injector complex include a high-intensity H+ beam, an H- beam, and polarized H+ and H- beams. Since simultaneous acceleration of H+ and H- beams will be attempted by the LAMPF accelerator, a dual beam-transport system for blending these beams into a common channel will be necessary in the injector area. Provision also is made for injecting either H+ or H- polarized beams into the system. A high-quality beam of protons (? cm-mrad emittance and 26 mA) has been produced by a von Ardenne duoplasmatron and a Pierce extraction accelerating column. Problems of simultaneous bunching and matching of H+ and H- beams of different intensities have been studied. The entire injector complex is under computer control and should provide reasonably sophisticated pulse programming flexibility.

Test of LASL Ion Source with 200-kV Pierce Accrelerating Column

A 200-kV test stand has been constructed for design evaluation of an ion source and accelerating column to operate at 750 kV. Requirements are a 6% to 12% duty factor for a 30-mA. pton pulse current with a normalized emittance (Area s?/?) of < 0.04 cm-mrad. The ion source is a Von Ardenne duoplasmatron with a large expansion cup. Beam extraction is accomplished by an exact Pierce geometry accelerating column. The test stand vacuum system uses a 1000 l/s ion pump capable of handling continuously the 2 atm-cc/min hydrogen throughput of the ion source. Pumping cells of the ion pwsp are expected to have a useful life in excess of 4000 h. The test stand can be completely operated by computer control. The test stand results indicate that the requirements at 750 kV can be realized.

Duoplasmatron Ion Beam Source for Vacuum Sputtering of Thin Films

A variation of the von Ardenne type of a duoplasmatron ion source is described. Here the arc discharge is maintained between the cathode in the high pressure and the anode in the vacuum chamber, as opposed to the conventional arrangement in which the arc discharge is confined primarily to the high pressure chamber. This modification allows the extraction, through apertures, of a well defined ion beam of current up to 500 mA over an area ∼1 cm2 into a vacuum chamber at a pressure of ∼10−5 Torr. The ion beam is accelerated and made to impinge on a target material for sputtering. Sequential sputtering of different targets inside the vacuum chamber is possible with the help of suitable magnetic fields. The ion beam has been used to sputter conducting, semiconducting, and insulating target materials. Typical rate of deposition of silver films at a distance of 8 cm from the target with a 50 mA, 2 kV ion beam of 8 mm diam is ∼400 Å/min. Deposition rates of ∼50 Å/min are obtained for SiO2 and TiO films. Vacuum sputtered films adhere to the subtrates much more strongly than the evaporated films do. Gold and silver films grow epitaxially on rock salt substrates at ambient or lower temperatures. This vacuum sputtering process has been found to induce and stabilize new structures. For example, sputtered films of molybdenum, tantalum, tungsten (normally bcc), and hafnium, rhenium and zirconium (normally hcp) have been observed to exist in an fcc phase. Fcc structure films as thick as 2 μ have been prepared. Epitaxial growth of the fcc structures on rock salt substrates at temperatures of ∼400°C are observed.

1213. Development trends in high-vacuum technology: M von Ardenne,Technik, No 8, 1965, 522–527 (in German)

1213. Development trends in high-vacuum technology: M von Ardenne,Technik, No 8, 1965, 522–527 (in German)

Special technological equipment for manufacturing thin-film components : M. von Ardenne, S. Schiller and U. Heisig, Nachrichtentechnik15, No. 8, p. 306 (1965)

Special technological equipment for manufacturing thin-film components : M. von Ardenne, S. Schiller and U. Heisig, Nachrichtentechnik15, No. 8, p. 306 (1965)

Ion Beam Analysis by an Electrostatic Technique

A method of spatially analyzing a positive ion beam by electrostatic means is presented. In this method, a small portion of a given ion beam passes through a low-density gas-filled chamber, where ionization and charge exchange products are collected and analyzed so as to reveal the original positive and neutral beam components. Results of a detailed spatial analysis of a 10-keV argon ion beam from a Von Ardenne duoplasmatron ion source are given and discussed. Comparison of integrated beam components with theoretical beam ``blowup'' indicates that microscopic and macroscopic neutralizations are the same within limits of the measurements.

Betriebserfahrungen und optimierung beim massenseparator mit reduziertem magnetfeldvolumen

In order to exploit the advantages inherent in the medium-size electromagnetic isotope separators at the Institute of stable Isotopes which have a large beam-current and a high transmission due to beam-cross-over, and a reduced magnetic field volume as originally proposed by M. von Ardenne, it is necessary to study the dependence of the two main characteristics, namely collector beam current and resolving power, vs the different operating variables. On the basis of this knowledge an exact optimisation of operating conditions is possible. It is shown that the suitable selection of the arbitrary variables, e.g. the heating power of the furnace, arc chamber and cathode, plays a fundamental role for an economic operation.

A source for the production of large dc ion currents

A source for the production of large ion currents has been developed based on the “duo-plasmatron” principle suggested by M. von Ardenne). Constant hydrogen ion currents in excess of 300 mA have been obtained with accelerating voltages up to 80 kV. The mass ratios of hydrogen ions have been analyzed magnetically with currents up to 100 mA. In this range, up to 70 per cent of the total current could be made H 2 + . The operating characteristics of the source were determined as the various parameters were independently varied.

On ion sources with high efficiency and intensity

The conditions determining the shape of the ion emitting plasma cap in ion sources are analysed. Dense plasmas (ni = 1014) give expanding caps like in the Von Ardenne source. Thin plasmas (ni = 1010) give inward bended caps like in all normal ion sources. This difference in shape means a difference in ion emission with a factor ten. The problem of an ion source with a high material efficiency is solved by the magnetic type ion sources. The Von Ardenne source has a high density plasma (ni = 1014) in the emission region with an extremely high electron temperature Therefore hardly any neutral particles are available. In the magnetic P.I.G. type sources the material efficiency is obtained by internal ion focusing. They run with low plasma density (ni = 1010). For the separation of microgram quantities of rare materials (radioactive or toxic like Pu) the P.I.G. type source should be preferred over the normally used arc source.

Duo Plasmatron Ion Source for Use in Accelerators

Evaluations of various sources for accelerator use at proton currents above 10 ma indicate that a variation of Von Ardenne's Duo Plasmatron will give performance superior to that of any other source presently available. Operating characteristics for various sizes of the source have been examined for H1+, H2+, H3+, H1−, He+, and He++ ions and electrons. Experience with protons in the current range from 1 to 30 ma indicates that the Duo Plasmatron can deliver up to 100 amp/cm2 of exit aperture area. Current densities such as this cannot be maintained in the accelerator-extractor section because of space charge forces, even at the highest gradients normally available for well-polished electrodes in vacuum; thus it can be said that proton current densities will be space-charge-limited by the accelerator rather than emission-limited by the source. Operation for He+ ions and electrons is similar to proton operation. Currents of 11 μa of H1− ions and 5 μa of He++ ions were extracted directly from a source which had been designed for a proton current of several milliamperes. The most striking features of the Duo Plasmatron are its remarkably high brilliance, high gas efficiency, good power economy, and compactness.

A Method for Preparing Rubber Latex Specimens for the Electron Microscope

Abstract The preparation of natural and synthetic rubber latex specimens for examination with an electron microscope is difficult because the individual particles are easily deformed and, under the usual conditions of specimen preparation, the particles tend to agglomerate. Von Ardenne and Beischer and others used a method which consisted of depositing a drop of highly diluted latex on a collodion film and allowing the drop to dry completely. In some instances the drop was withdrawn again into a glass capillary. It was found that in either case the latex particles were flattened at their areas of contact with the collodion film. The collodion film method was tried in this laboratory with the same poor results observed by Hendricks, Wildman, and McMurdee. Figure 1 is an electron micrograph of a natural rubber latex particle deposited by evaporating latex diluted 200 to 1 on a collodion film. The film has broken and curled to give a profile view of the particle which is observed to be badly flattened at its area of contact with the film. Figure 2 is a typical electron micrograph of natural rubber latex particles deposited on a collodion film. The blurred outlines of the particles are explained by the effect shown in Figure 1. It was obviously impossible to make good particle-size measurements from micrographs of this type. It was found further that severe aggregation of particles usually took place when a drop of the diluted latex was dried down. The latex particles which were left behind when the drop was removed with a glass capillary usually were not badly agglomerated, but it was felt that there was some possibility that the latex particles might adhere selectively according to size to the collodion film. An attempt was made to reduce the amount of agglomeration by incorporating in the diluting water various amounts of such wetting or dispersing agents as sodium oleate, orvis paste, Aerosol-OT, and ammonium caseinate. None of these materials helped very much in reducing the agglomeration of particles. It was found also in this study that very often the latex particles appeared granular around their edges due to foreign material being swept in during the evaporation of the water and crystallizing out upon the surface of the particle. This effect may also be observed in Figure 1.