Articles With Citations to Z. Abou-Assaleh

Theoretical Plasma Physics

 Controlled Thermonuclear Fusion Energy

1990

Physics of Fluids B: Plasma Physics -- October 1990 -- Volume 2, Issue 10, pp. 2448-2455

https://doi.org

Plasma evolution from laser-driven gold disks. II. Computational design and analysis

D. Ress and L. J. Suter

Lawrence Livermore National Laboratory, P. O. Box 808, L-473, Livermore, California 94550

E. F. Gabl and B. H. Failor

KMS Fusion, Inc., 700 KMS Place, P. O. Box 1567, Ann Arbor, Michigan 48106

(Received 12 March 1990; accepted 11 June 1990)

ABSTRACT
The lasnex computer code [Comments Plasma Phys. Controlled Fusion 2, 51 (1975)] was used in the design and analysis of an experimental study of laser‐driven plasma blowoff from gold disks. In the study, several temporal profiles of 0.53 mm laser illumination were used, including square pulses, picket pulse trains, and pulses with graduated leading edges. Preliminary modeling suggested diagnostic techniques [time‐ and space‐resolved imaging of M‐band x‐ray emission and time‐ and space‐averaged measurements of high‐energy (3.5–20 keV) x‐ray spectra] that complemented diagnostics already used in such experiments (four‐frame holographic imaging to determine the electron‐density profile in the underdense corona plasma). In this article, the lasnex results are analyzed and are compared with the measured plasma electron‐density profiles and with time‐ and space‐averaged measurements of the corona temperature. The simulation tracks the observed electron‐density profiles fairly well during the early portions of the laser drive, during which the spatial profiles are approximately self‐similar, but overestimates the electron density in the later, steady‐state segment of the profile. For the corona electron temperature, simulation and experiment agree to within the experimental accuracy of ±20%.

REFERENCES

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16.  J. H. Rogers, J. S. DeGroot, Z. Abou-Assaleh, J. P. Matte, and M. D. Rosen, Phys. Fluids B 1, 741 (1989).

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Physics of Plasmas 2, 1725 (1990);

https://doi.org/10.1063/1.859581

Phys. Fluids B 2 (8) August 1990 (1725)

"Nonlocal heat transport in plasmas down steep temperature gradients"

F. Minotti and C. Ferro Fontan

 

ABSTRACT

An analytic solution to the problem of nonlocal heat transport in plasmas by electrons whose range is not short compared to the temperature scale length is presented. The formalism extends the results of Albritton et al. [Phys. Rev. Lett. 57, 1887 (1986)] to an arbitrary ionization state Z. This simple transport scheme is checked against recent experiments in the AURORA device [Phys. Fluids B 1, 741 (1989)]. The agreement, both for the measured cold electron temperature profile and the plasma potential, is very good and comparable to the result of full kinetic calculations.

REFERENCES

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1.  J. H. Rogers, J. S. De Groot, Z. Abou-Assaleh, J. P. Matte, T. W. Johnston, and M. D. Rosen, Phys. Fluids B 1, 741 (1989). Google ScholarScitation

https://doi.org/10.1063/1.859581

Journal of Nuclear Materials

Volumes 176–177, 3 December 1990, Pages 1055-1058

"VUV fluorescence diagnostics of sputtered oxygen and carbide materials"

A.Goehlich, M.Röwekamp, H.F.Döbele

Institut für Laser- und Plasmaphysik, Universität GH-Essen, D-4300 Essen, Fed. Rep. Germany

Abstract

Sputtering of oxygen, carbon, boron and silicon atoms and detection with laser-induced fluorescence (LIF) spectroscopy in the vacuum ultraviolet (VUV) is described. The necessary pump radiation at λ = 130 nm (O) and λ = 166 nm (C, B, Si) is generated by stimulated Raman scattering (SRS) in H₂. The generation of the VUV pump radiation by SRS is briefly described. Measurements of velocity distributions and resulting surface binding energies as well as concentrations and yields are reported.

https://www.sciencedirect.com/science/

article/abs/pii/002231159090191O

Journal of Nuclear Materials

Volumes 176–177, 3 December 1990, Pages 1059-1063

https://doi.org/1

"Measurement of pre-sheath flow velocities by laser-induced fluorescence"
S.L.Gulick, B.L.Stansfield, Z.Abou-Assaleh, C.Boucher, J.P.Matte, T.W.Johnston, R.Marchand
INRS-Energie, CP 1020, Varennes, Québec, Canada J3X 1S2

Abstract
For the first time, the pre-sheath ion flow velocity has been measured using the Doppler shift of laser-induced fluorescence in singly-ionized argon ions. The velocity shows a monotonic increase, from a value of about 0.15 of the sound speed VS far from the target to 0.5 of Vs at a distance of 5 mm from the surface. The temperature, the floating potential and the density are calculated from cylindrical probe measurements taken in the same region under identical conditions. These experimental results are compared with those from a 1D isothermal single-ion fluid model of the pre-sheath and a kinetic electron/fluid ion model. Both models agree well with the density profile, but underestimate the potential change and overestimate the velocity. In addition, the bulk flow velocity has been independently determined from “Mach probe” measurements, using various candidate theories to relate the Mach number to the ratio of the upstream to downstream saturation currents. Comparison with the optical measurements indicate that the probe models which include viscosity provide reasonable agreement with our Mach probe data.

Physics of Fluids B: Plasma Physics 2, 1247 (1990);

https://doi.org/

"Nonlocal fluxes at a plasma sheath"
R. Marchand, Z. Abou‐Assaleh, and J. P. Matte
INRS‐Energie, C. P. 1020, Varennes, Quebec, J3X 1S2, Canada

ABSTRACT
The particle and energy fluxes of electrons at the boundary of a plasma in contact with a perfectly absorbing plate are considered. In general, the fluxes are shown not to be determined by the plasma temperature and density at the plate but rather by a convolution of the plasma profiles in the vicinity of the plate. A simple empirical expression is proposed for the nonlocal fluxes, which approximately reproduces the results of a full kinetic calculation. The implications of this, to divertor plasmas near the neutralizer plate, are discussed.

Journal of Nuclear Materials
Volumes 176–177, 3 December 1990, Pages 837-840
https://doi.org/

Time-resolved thermal load measurements on the FT limiter
G.Maddaluno, M.Ciotti, C.Ferro
Associazione Euratom-ENEA sulla Fusione, CRE Frascati, 00044 Frascati, Rome, Italy

Abstract
Time-resolved measurements of the heat flux on the FT poloidal limiter were carried out during the last experimental period of the machine. The temperature increase of the limiter support was measured on both the ion and the electron side by thermocouples that were directly exposed to the plasma at four poloidal positions. Strong poloidal as well as directional (electron versus ion side) asymmetries were found, which are partially attributed to the length variation of the magnetic field line intercepted by the limiter as the plasma position changes. A typical trend of the power flux to the limiter was also inferred, which is similar for both low and high density discharges.

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