الفهرس 
The Beam-Plasma interactionOnly 14 pages are availabe for public view
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Abstract
nteractions with dense plasmas have many forms such as interactions of laserplasma,
wave-plasma, beam-plasma, and plasma-matter interactions.
In this study, beam-plasma interactions and plasma-matter interactions have
been investigated. These two forms of interactions have important roles inside the
fusion reactor. Beam-plasma interaction is used in plasma heating which is the main
requirement for achieving fusion. The plasma –matter interaction is very useful for
studying the performance of plasma facing materials inside the fusion reactors.
In the first part of this study , the electron beam interaction with semi-bounded
quantum magnetized plasma using the quantum hydrodynamic model (QHD) have
been modified to incorporate the excitation of the transverse mode (TM) of surface
modes. The wave equation which describes the excited fields has been solved to
obtain the dispersion relation for these modes at different cases (magnetized or
unmagentized, classical or quantum plasma). It is found that the quantum effects
play an important role for frequencies both lower and higher than plasma frequency
such that the phase velocity of modes increase with increasing the quantum effects
compared to the classical case. It has been also displayed that in the absence of
external magnetic field the surface modes appear in the all regions of the wavelength
while they have been only excited for high wave number in the presence of the
magnetic field. Besides, it has been shown that the dispersion curves of the modes
depend essentially on the density ratio of beam and plasma.
In the second part of this study, a transverse to the other kind of plasma
interaction namely plasma-matter interaction. This kind of interaction is adequate for
studying the performance of Plasma-facing materials (PFM) in future large tokamaks
which will suffer from ablation due to expected hard disruptions. This ablation
affects the reactor interior lining tiles and the divertor modules. Ablation and
surface evaporation due to the intense heat flux from disruption is associated with
ionization of the evolved particulates. Generated ions at such plasma conditions may
allow for higher ionization states such that the plasma at the boundary can be
composed of electrons, ions (first, second and third ionization) and excited atoms.
The boundary layer is dense and tends to be weakly nonideal. The NC State
University electrothermal plasma code (ETFLOW) used and modulated to simulate
the high heat flux conditions in which the carbon liner tested for simulated heat
fluxes for transient discharge period of 100μs, with full width at half maximum
(FWHM) of ~50μs, to provide a wide range for obtaining reasonable good fits for
the scaling laws. Transient events with ~10MJ/m2 energy deposition over short
transient of 50-100μs would produce heat fluxes of 100 – 200 GW/m2. The heat flux
range in this simulation is up to 288 GW/m2 to explore the generation of carbon
plasma up to the third ionization C+++. The generation of such heat fluxes in the
electrothermal plasma source requires discharge currents of up to 250 kA over a
100μs pulse length with ~50μs FWHM. The number density of the third ionization is
six orders of magnitude less than the first ionization at the lowest heat flux and two
orders of magnitude less at the highest heat flux. Plasma temperature varies from
31,600K (2.722eV) to 47,500K (4.092eV) at the lowest and highest heat fluxes,
respectively. The plasma temperature and number density indicate typical highdensity
weakly nonideal plasma. The evolution of such high-density plasma
particles into the reactor vacuum chamber will spread into the vessel and nucleate on
the other interior components. The lifetime of the PFCs will shorten if the number of
hard disruptions at such extreme heat fluxes would be increasing, resulting in major
deterioration of the armor tiles.