Bibliothek

X
feed icon rss

Ihre E-Mail wurde erfolgreich gesendet. Bitte prüfen Sie Ihren Maileingang.

Leider ist ein Fehler beim E-Mail-Versand aufgetreten. Bitte versuchen Sie es erneut.

Vorgang fortführen?

Exportieren
Filter
Datenquelle
Materialart
Erscheinungszeitraum
Schlagwörter
  • 1
    Digitale Medien
    Digitale Medien
    Broadband tunability of a far-infrared free-electron laser (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 1501-1509 
    Details
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: A unique property of the free-electron laser (FEL) is its capability to be tuned continuously over a wide spectral range. This is a major difference with all other high-power lasers. However, the tunability of first-generation FELs used to be quite poor (typically 10% or less), due to constraints imposed by the accelerator and the undulator. The free electron laser for infrared experiments (FELIX) uses an undulator with an adjustable gap, which permits wavelength scans over an octave in typically 2 min without the need for any readjustment of the electron beam. Results obtained in operation of the long-wavelength FEL of the FELIX facility are presented. These involve measurements of the spectral range covered (16–110 μm), the output power, and the influence of the cavity desynchronism. The results are compared with numerical simulations.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.354849
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 2
    Digitale Medien
    Digitale Medien
    Measurements of the length of intense electron bunches using a capacitive probe and a 20-GHz sampling oscilloscope (1991)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 62 (1991), S. 2904-2909 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Measurements of the longitudinal profile of intense electron bunches with an energy of 100 keV, using a button monitor and a 20-GHz sampling oscilloscope, are presented in this paper. At this energy, which is intermediate between nonrelativistic and relativistic, the button response is quite different from the response in either of the two extreme cases. An analytical model of the response is presented. The resolution derived from this model is 80 ps at 100-keV beam energy. For more relativistic beams, a resolution of about 40 ps appears to be feasible. Great care has to be taken in avoiding resonances.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1142179
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 3
    Digitale Medien
    Digitale Medien
    On the phase velocity of plasma waves in a self-modulated laser wake-field accelerator (1996)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 3 (1996), S. 3121-3128 
    Details
    ISSN: 1089-7674
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: The properties of the wake field excited by a flattop laser pulse with a sharp leading edge and a power below the critical one for relativistic self-focusing are studied analytically and numerically with emphasis on the phase velocity of the plasma wave. The paraxial model describing modulation of the pulse spot size is shown to provide a good quantitative description, including preexponential factors, of the wake field during the linear stage of the resonant self-modulation instability. Though the phase velocity of the excited plasma wave is shown to be close to the group velocity of the laser pulse, the relativistic γ-factor corresponding to the phase velocity, which is a crucial parameter for particle acceleration, can be substantially less than that of the group velocity. Fortunately, for the considered three-dimensional regime of self-modulation, the noticeable difference between these two γ-factors takes place only in the initial stage of the instability and vanishes in the later stages. © 1996 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.871659
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 4
    Digitale Medien
    Digitale Medien
    A 50 MW pulse-forming network with a voltage stability within 0.03% (1993)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 64 (1993), S. 568-576 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: Requirements on electron energy stability are extremely tight for operation of a free-electron laser. In case a radio-frequency field is used to accelerate the electrons, this leads to stringent requirements on the stability of the klystron output power and, hence, on the stability of the source producing the cathode voltage. A pulse-forming network (PFN) capable of delivering a 19 kV pulse with a stability of 0.03%, during 20 μs, is presented. The PFN consists of four parallel lines, each containing 19 cells of a 20 nF capacitor and a 20 μH solenoid. The solenoids are equipped with taps and a plunge tuner. An innovative line switch is used, namely a stack of 32 thyristors in series. Numerical simulations of the pulse shape show that, in order to obtain the best possible pulse flatness, it is essential to arrange the capacitors such that the difference between adjacent capacitances is minimized.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1144234
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 5
    Digitale Medien
    Digitale Medien
    Time-resolved electron spectrum diagnostics for a free-electron laser (1996)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 67 (1996), S. 641-648 
    Details
    ISSN: 1089-7623
    Quelle: AIP Digital Archive
    Thema: Physik , Elektrotechnik, Elektronik, Nachrichtentechnik
    Notizen: 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. © 1996 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.1146835
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 6
    Digitale Medien
    Digitale Medien
    Negative ion formation at a barium surface in contact with a hydrogen plasma (1987)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 51 (1987), S. 1495-1497 
    Details
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Measurements on the production of negative hydrogen ions at a barium surface, in contact with a hydrogen plasma, are presented and discussed. In spite of the high work function of barium compared to more conventional cesiated converter surfaces, considerable yields of negative ions were produced. Conversion efficiencies up to 4% were achieved. No negative barium ions were observed.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.98613
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 7
    Digitale Medien
    Digitale Medien
    Multichannel acceleration of intense, low-energy ion beams (1987)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 62 (1987), S. 4335-4344 
    Details
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: We present measurements on multichannel acceleration of intense, low-energy ion beams with a multiple electrostatic quadrupole array linear accelerator. The beam properties are investigated for different transverse and longitudinal focusing strengths, which can be adjusted independently in the accelerator. A maximum He+ ion current of four times 2 mA has been accelerated from 40 to 115 keV with an acceleration efficiency of 50%. Measurements and computer simulations suggest that the current is limited by transverse fields and by mismatch and misalignment of the beams, whereas longitudinal fields are of minor importance. The energy spread in the bunches is roughly three times the gap voltage.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.339066
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 8
    Digitale Medien
    Digitale Medien
    The role of cesium-ion bombardment in the formation of negative hydrogen ions on a converter surface (1987)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 61 (1987), S. 5000-5011 
    Details
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: A fundamental study of the formation of negative hydrogen ions via surface conversion is presented. Employed is a novel type of converter, namely a porous tungsten button with liquid cesium flowing through it towards the side which is in contact with the plasma. A high cesium coverage, i.e., a small work function, can easily be maintained with this approach. This is related to the high flux of neutral cesium atoms to which the converter is exposed and to the small cesium density in the discharge. Despite the small work function, we obtain negative-ion yields which are an order of magnitude smaller than is usually found in more conventional experiments, in which the converter is cesiated via injection of cesium vapor into the discharge. Furthermore, our energy distributions show that no negative ions are formed via desorption by cesium-ion impact. This gives a strong indication that the extracted negative hydrogen ions are primarily formed via this process in cesium seeded discharges. Our view is confirmed by the observation that the negative-ion yield increases with an order of magnitude when a small amount of argon gas is injected into the discharge.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.338320
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 9
    Digitale Medien
    Digitale Medien
    Negative ion formation at a barium surface exposed to an intense positive-hydrogen ion beam (1988)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 64 (1988), S. 3863-3873 
    Details
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: A fundamental study of the formation of negative hydrogen ions via surface conversion is presented. Employed is a novel type of converter, namely a pure barium metal surface. In spite of the high work function of barium compared to more conventional cesiated converters, considerable yields of negative ions were produced. Conversion efficiencies up of 4% are obtained, which is of the same order as for cesiated converters. The high negative-ion yield is probably related to the electron density of barium, which is almost twice that of cesiuim. This is confirmed by model calculations and by UHV scattering experiments under well-defined conditions. Furthermore, calculations showed that the hydrogen coverage of the converter increases with increasing flux of positive hydrogen ions to the surface. This behavior is confirmed experimentally. Seeding the hydrogen plasma with argon has no significant effect on the conversion efficiency. This is believed to be related to the competition between the lowering of the surface hydrogen coverage and the increase of the hydrogen desorption rate, both due to the higher sputter coefficient of argon compared to hydrogen.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.341340
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 10
    Digitale Medien
    Digitale Medien
    Formation of negative hydrogen ions on a coadsorbed layer of cesium and hydrogen on W(110) (1986)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 59 (1986), S. 241-248 
    Details
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Negative ion formation on a W(110) surface which is covered with a coadsorbed layer of cesium and hydrogen is studied by scattering a proton beam from such a surface. The primary energy is 400 eV. The angle of incidence is 70° with respect to the surface normal. The hydrogen exposure ranges from 0 to 3000 L. The negative ion formation probability on a surface with 0.6 times the saturation cesium coverage is reduced by a factor of 4 by a hydrogen exposure of 3000 L. At small coverage the reduction is found to be proportional to the number of adsorbed hydrogen atoms. The formation probability on a surface which is covered with a thick cesium layer is hardly affected by a similar exposure. These phenomena are attributed to resonant electron transfer between a negative ion and an adsorbed hydrogen atom.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.336871
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
Schließen ⊗
Diese Webseite nutzt Cookies und das Analyse-Tool Matomo. Weitere Informationen finden Sie hier...