Beam extraction

An electrostatic mirror can be produced by an electrode at a potential energy that is greater than the kinetic energy divided by the charge of the particle. The bending and focusing power of electrostatic systems are limited by the maximum electric fields that can be applied across the electrodes. Extensive electrostatic systems have been constructed for the transport of low-energy beams, KE < 50 keV, for example, beams extracted from ion sources are usually transported with electrostatic elements. 

It has been the purpose of this paper to provide an overview of the basic differences and similarities of the various types of Instruments which detect Ionized particles emitted from surfaces by energetic particle bombardment. Since the scope of secondary ion mass spectrometry Is so broad, It is not surprising that no one Instrument has been designed to perform optimally for all types of SIMS analyses. Design aspects of the primary beam, extraction optics, mass spectrometer, detection equipment and vacuum system must be considered to construct an Instrument best suited for a particular purpose. 

The mass-separated ion beams extracted from the proposed system would be directed to various experimental devices capable of determining basic nuclear properties such as half-life, spin, nuclear moments, mass, and nuclear structure. The data acquired would have broad application to theories of nuclear matter and to such related topics as nucleosynthesis of the elements. We... 

The features mentioned above show that IBA techniques and particularly PIXE, because of its high sensitivity, constitute an extremely useful tool for the knowledge and the preservation of cultural heritage. A decisive improvement has been achieved in developing an experimental set-up permitting the direct analysis of objects without sampling. This is carried out by means of a 20-pm diameter micro-beam extracted in air through an ultra-thin exit window, as shown in fig. 3 [10],... 

An ion beam extracted from the ion source passes to the mass separation system where continuous changes in the voltages applied to the electrodes allow ions of the appropriate mass/charge (M/Z) ratio to achieve stability in the mass filter and pass to the detector. A spectrum is therefore generated giving the variation of the amplitude of the... 

Mass bias in ICP/MS is 10 times more severe than in other types of mass spectrometry, on the order of 1%/amu. The observed bias is sensitive to both sample composition and instrument ion optical tuning conditions. The source of this bias is dominated by space charge effects in the ion beam extracted from the ICP (Douglas and Tanner, 1998). 

Irradiation positions in neutron beams extracted from reactors are most conunonly used for PGAA. These positions offer a major advantage namely the samples do not require packaging to withstand mechanical and irradiation stresses, i.e., containment can be minimal or is not required at all. In principle, samples are not limited to a certain size and shape, except by the physical space in the irradiation position, which commonly has shielding elements put in place to protect persormel. Nevertheless, irradiation of entire paintings has been demonstrated (Fischer et al. 1987). 

The dominant neutron sources in laboratory PGAA are beams extracted from research reactors. Other neutron sources, based on radioactive nuclides or neutron generators, commonly used... 

The molecular beam extracted by a skimmer is interrogated in two different ways. First, an Nd YAG laser is used to ionize the species of interest. Second, in order to carry out photodepletion experiments, the second-harmonic output of the same Nd YAG laser is split into two beams, one of which is doubled to give... 

It turns out that the conditions are such that a buffer-gas beam extracted in the hydrodynamic regime will be boosted, meaning that the forward velocity of the molecules will be higher than their mean thermal velocity. This can be seen by noting that for > 1, Equation 13.14 can be expressed as... 

Hard BN films obtained by an ion beam extracted from a borazine plasma were investigated in order to examine their adhesion and friction behavior. It was shown that sputter-cleaned film surfaces exhibit strong interfacial adhesion and high friction. The presence of adsorbates on the BN surfaces reduces their shear strength [116 to 118]. 

Positron beam extraction (electric and magnetic field equipment, high voltage, high vacuum equipment. 

Fig. 3.6. A typical example of the design of converter, moderator, and beam extraction geometry, a water cooled tungsten converter b tungsten moderator vanes c repeller electrode d first element of extraction system. Adapted from Ebel et al. [3.16].

When beam port experiments are installed the plugs are usually removed. In most cases colimators or selective absorbers are placed in the beam port and the beam is extracted from the shield, used in an experiment, and then absorbed in a "beam catcher". In order to allow for shielding when the beam port experiment is not in use, the usual facility practice is to replace the other (8-inch) plug with an aluminum tank that can be filled with water to stop the beam (or drained when beam extraction is desired). 

Figure 17.13 (a) Bright field transmission electron microscopy image of 316L(N) specimen exposed to liquid sodium with about 40 ppm oxygen at 550°C for 5000 h, after focused ion beam extraction, (b) Diagram of the mechanisms occurring in liquid sodium [24]. 

IIS Beams were selected among vital LHC components, for their ability to prevent the injection and circulation of beams, and this, in parallel to the beam extraction system. The elements preventing injection are mobile absorber blocks, horizontal dipole magnet chains, and injection septa magnets. They are located in tunnels ensuring the beam transfer between the SPS (Super Proton Synchrotron) accelerator and the LHC. In each injection tunnel, three IIS Beams define an interlock chain, named LHC2 chain and LHC8 chain, respectively. 

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