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  • 1
    Electronic Resource
    Electronic Resource
    Z-discharge transport of intense ion beams for inertial confinement fusion (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 70 (1991), S. 5292-5305 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Ion inertial confinement fusion requires beam transport over distances of a few meters for isolation of the diode hardware from the target explosion and for power compression by time-of-flight bunching. This paper evaluates light ion beam transport in a wall-stabilized z-discharge channel, where the discharge azimuthal magnetic field radially confines the ion beam. The ion beam is focused onto the entrance aperture of the transport channel by shaping the diode to achieve beam convergence in a field-free drift region separating the diode from the transport section. Ion orbits are studied to determine the injection efficiency (i.e., the fraction of the beam emitted from the diode which is transported) under various conditions. Ions that are focused onto the channel entrance at too large of an angle for confinement hit the wall and are lost. For a multimodular scheme (10–30 beams), individual transport channels are packed around the target with the exit apertures at some standoff distance from it. The fraction of the beam that is lost in this field-free standoff region is also evaluated under various conditions. The standoff efficiency is then combined with the injection efficiency to give the dependence of the total transport efficiency ηt on diode, focusing, transport and standoff parameters. It is found that ηt can be in the range of 75%–100% for parameter values that appear to be achievable.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.350239
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  • 2
    Electronic Resource
    Electronic Resource
    Wire-guided transport of intense ion beams (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 69 (1991), S. 639-655 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Light ion inertial confinement fusion requires beam transport over distances of a few meters for isolation of the diode hardware from the target explosion and for power compression by time-of-flight bunching. This paper evaluates a wire-guided transport system that uses the azimuthal magnetic field, produced by a current driven through a thin wire, to radially confine the ion beam. Ion orbits are studied to determine the injection efficiency (i.e., the fraction of the beam which is transported) under various conditions. Some ions hit the wire because of too small angular momentum at injection; others hit the wire or are lost to large radius during transport because of chaotic orbit behavior induced by a small number of return-current wires close to the beam envelope. For a multimodular scheme (10–30 beams), individual transport system are packed around the target at some standoff distance. The fraction of the beam which is lost in this field-free standoff region is also evaluated under various conditions. The standoff efficiency is then combined with the injection efficiency to give the dependence of the total transport efficiency, ηt, on diode, focusing, transport, and standoff parameters. It is found that ηt can be as large as about 60% for parameter values which appear to be achievable.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.347344
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  • 3
    Electronic Resource
    Electronic Resource
    Theoretical modeling and experimental characterization of a rod-pinch diode (2001)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 8 (2001), S. 4618-4636 
    Details
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The rod-pinch diode consists of an annular cathode and a small-diameter anode rod that extends through the hole in the cathode. With high-atomic-number material at the tip of the anode rod, the diode provides a small-area, high-yield x-ray source for pulsed radiography. The diode is operated in positive polarity at peak voltages of 1 to 2 MV with peak total electrical currents of 30–70 kA. Anode rod diameters as small as 0.5 mm are used. When electrode plasma motion is properly included, analysis shows that the diode impedance is determined by space-charge-limited current scaling at low voltage and self-magnetically limited critical current scaling at high voltage. As the current approaches the critical current, the electron beam pinches. When anode plasma forms and ions are produced, a strong pinch occurs at the tip of the rod with current densities exceeding 106 A/cm2. Under these conditions, pinch propagation speeds as high as 0.8 cm/ns are observed along a rod extending well beyond the cathode. Even faster pinch propagation is observed when the rod is replaced with a hollow tube whose wall thickness is much less than an electron range, although the propagation mechanism may be different. The diode displays well-behaved electrical characteristics for aspect ratios of cathode to anode radii that are less than 16. New physics understanding and important properties of the rod-pinch diode are described, and a theoretical diode current model is developed and shown to agree with the experimental results. Results from numerical simulations are consistent with this understanding and support the important role that ions play. In particular, it is shown that, as the ratio of the cathode radius to the anode radius increases, both the Langmuir–Blodgett space-charge-limited current and the magnetically limited critical current increase above previously predicted values. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1403016
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  • 4
    Electronic Resource
    Electronic Resource
    Self-pinched transport of an intense proton beam (2000)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 7 (2000), S. 346-358 
    Details
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Ion beam self-pinched transport (SPT) experiments have been carried out using a 1.1-MeV, 100-kA proton beam. A Rutherford scattering diagnostic and a LiF nuclear activation diagnostic measured the number of protons within a 5 cm radius at 50 cm into the transport region that was filled with low-pressure helium. Time-integrated signals from both diagnostics indicate self-pinching of the ion beam in a helium pressure window between 35 and 80 mTorr. Signals from these two diagnostics are consistent with ballistic transport at pressures above and below this SPT pressure window. Interferometric measurements of electron densities during beam injection into vacuum are consistent with ballistic transport with co-moving electrons. Interferometric measurements for beam injection into helium show that the electron density increases quadratically with pressure through the SPT window and roughly linearly with pressure above the SPT window. The ionization fraction of the helium plateaus at about 1.5% for pressures above 80 mTorr. In the SPT window, the electron density is 3 to 20 times the beam density. Numerical simulations of these beam transport experiments produce results that are in qualitative agreement with the experimental measurements. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.873803
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  • 5
    Electronic Resource
    Electronic Resource
    High-fluence large-area MeV proton-beam diagnostics : Eighth topical conference on high−temperature plasma diagnostics (1990)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 61 (1990), S. 3122-3124 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The spatial distribution of intense MeV pulsed proton beams over 100 cm2 area is measured with two techniques. An array of carbon-activation samples gives fluences of 100–400 J/cm2 with 1–2 cm resolution. Continuous distributions with 3–4 mm resolution are obtained by imaging proton-induced Al K-line x rays.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1141701
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  • 6
    Electronic Resource
    Electronic Resource
    Erratum: "Theoretical modeling and experimental characterization of a rod-pinch diode" [Phys. Plasmas 8, 4618 (2001)] (2002)
    [S.l.] : American Institute of Physics (AIP)
    Physics of Plasmas 9 (2002), S. 3643-3643 
    Details
    ISSN: 1089-7674
    Source: AIP Digital Archive
    Topics: Physics
    Notes: © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1493795
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  • 7
    Electronic Resource
    Electronic Resource
    Sodium-fluoride discharge for fast Z-pinch experiments (1989)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 65 (1989), S. 2664-2672 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A capillary-discharge plasma source has been developed to produce a sodium-bearing plasma for fast Z-pinch implosion experiments. Peak currents of 40–50 kA from a 0.5-kJ capacitor bank were driven through a 0.5-mm-diam, few cm long capillary drilled in packed sodium-fluoride powder to form the source. A nozzle was used to collimate plasma ejected from one end of the capillary to produce a 1–2-cm-diam, several cm long cylindrical plasma. Ions with velocities of 2.2–3.4 cm/μs and densities of up to 5×1015 cm−3 were measured with biased charge collectors located at least 5 cm from the nozzle. Measurements of visible light from neutrals near the nozzle exit gave velocities of 1.5–1.7 cm/μs. Indications of axial and radial nonuniformities of the plasma were observed in framing photographs of visible-light emission and in spatially resolved spectral measurements. Neutral-sodium and neutral-fluorine lines were identified in the spectral range from 2300 to 6700 A(ring). Also, impurity lines of carbon, copper, and hydrogen were identified and used to characterize the plasma. Stark broadening of the Balmer alpha line of hydrogen was used to deduce a peak electron density of 8×1016 cm−3 at the exit of a 2-cm-diam nozzle. Electron temperatures of 1.4–1.6 eV at the nozzle exit were inferred from relative intensities of the C i and C ii lines. At this density and temperature, Saha-equilibrium-model calculations indicate that the plasma consists primarily of singly ionized sodium and neutral fluorine. A total mass per unit length (sodium and fluorine) of at least 15 μg/cm is deduced from this analysis of the plasma constituents. This capillary discharge has been used to produce 50–100 GW of sodium K-shell x rays in fast Z-pinch experiments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.342749
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  • 8
    Electronic Resource
    Electronic Resource
    The theory of final focusing of intense light ion beams (1990)
    New York, NY : American Institute of Physics (AIP)
    Physics of Fluids 2 (1990), S. 378-389 
    Details
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Efficient transport of the high-power light ion beams of interest to inertial confinement fusion (ICF) experiments may require the use of large radius transport channels. The mismatch in the radii of the transported ion beam and the ICF target requires that the beam be focused following transport. A theoretical description of intense light ion beam focusing with a z-discharge plasma is presented. The theory is based on a Vlasov equation description of a fully charge- and current-neutralized ion beam, neglecting any angular momentum of the beam ions. An initial ion beam phase-space distribution with adjustable parameters is considered so that its effect upon the phase-space distribution at the focal plane can be analyzed. A numerical code is used to analyze the effect of angular momentum on the focusing properties of the final focusing cell. The theoretical analysis gives expressions for the focal length, for the discharge current required to produce a given degree of focusing, and for the radial number density profiles at the focal plane. The analysis of angular momentum indicates that the focal length and focusing current are not strongly affected even when beam ions have a significant amount of angular momentum.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.859326
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  • 9
    Electronic Resource
    Electronic Resource
    Physiology of Fibronectin (1984)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Medicine 35 (1984), S. 561-575 
    Details
    ISSN: 0066-4219
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1146/annurev.me.35.020184.003021
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  • 10
    Electronic Resource
    Electronic Resource
    Physiology of Thrombospondin (1990)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Medicine 41 (1990), S. 85-97 
    Details
    ISSN: 0066-4219
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1146/annurev.me.41.020190.000505
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