[en] In this paper, a new plasma diagnostic method based on a theoretical model which permits the calculation for the associated admittance with a cylindrical or spherical ion sheath probe is reported. In this way a theoretical curves set of the ion sheath capacitance versus frequency, for several electron densities and temperatures is obtained. The identification with the appropriate theoretical curve of any experimental value of ion sheath capacitance permits to obtain the electron plasma density and temperature. The results obtained with this method are in agreement with the experimental values obtained by using the I-V characteristic method. This new method has advantage over other diagnostic techniques based on Langmuir probes, since the probe current and therefore the plasma perturbation is very small. (author)

[en] A new theoretical model about the ion currents to a cylindrical probe has been developed which takes into account the influence of a finite ion temperature value. The ABR (Allen, Boyd and Reynolds) model, which considers only radial motion for the positive ions, is recovered in the limit of cold ions. In this paper we axe going to show the experimental ion currents obtained in a plasma in which the positive ion temperature effect cannot be neglected

[en] As it is known, the experimental ion currents to a cylindrical Langmuir probe fit quite well to the radial motion theory, developed by Allen, Boyd and Reynolds (ABR Model) and generalized by Chen for the cylindrical probe case. In this paper, we are going to develop a generalization of the ABR theory, taking into account the influence of a finite ion temperature value

[en] Neutron-irradiated InP:Fe semi-insulating crystals have been investigated by photoluminescence (PL) and Hall effect. The evolution of the different PL transitions was studied as a function of the thermal neutron dose, annealing temperature and excitation power. Hall effect measurements confirm the success of the doping technique in semi-insulating InP:Fe. For tin concentration higher than 6x10¹⁵ cm^-3 the InP:Fe samples annealed at 550 deg. C are clearly n-type with a free carrier concentration slightly lower than the calculated tin concentration

[en] A theoretical model that allows the analytical calculation of the associated admittance of an ion-sheath of cylindrical and spherical probes near the ion plasma frequency is reported. Theoretical results are compared with experimental data which are in agreement. (author)

[en] The single Langmuir probe method has been used to determine the relaxation rates of the electron density and temperature in an argon afterglow dc cylindrical plasma. The ion-electron recombination was found to be the fundamental mechanism of density decay during the early afterglow while the ambipolar diffusion controlles the density decay for later afterglow. Electron temperature cooling curves have been interpreted via electron-neutral collisons. Measurements of the electron-ion recombination and the ambipolar diffusion coefficients have been made, as well as of the electron-neutral collision frequency and the momentum transfer cross sections. Good agreement is obtained with previously published data. (author)

No abstract available

[en] Analytical expressions to determine sheath thickness surrounding cylindrical or spherical Langmuir probes are obtained using a radial model for cold electropositive plasmas. As has been shown by the authors, a radial model can be used to obtain numerical results to locate the sheath edge considering three different criteria, when it is parameterized according to the radius and the potential of the probe. Expressions to fit these results are provided

[en] The interface between a metallic plane surface and an electro-negative plasma is analyzed by using a theoretical model. The model includes ionization, positive ion collisions and positive ion thermal motion. Some physical quantities of great interest in plasma surface treatment and plasma diagnostic are analyzed, such as the positive ion current collected by the metal and the floating potential. The effect produced by each process (collisions, ionizations and positive ion thermal motion) is analyzed

[en] To harness fusion energy is one of today's greatest technological challenges, and one well worth pursuing. Success in the development of fusion power would result in a virtually inexhaustible source of energy. The fusion reaction, the process that powers the sun and the stars, can be duplicated on Earth. However, to date these fusion processes have been the products of large-scale experimental efforts. They have yet to achieve fusion in a manner that is cost effective and efficient enough to be applied in a commercial reactor. Lawrence Livermore National Laboratory (LLNL) has been centrally involved in the Nation's inertial confinement fusion (ICF) program for over 25 years. Much of the focus of the LLNL ICF Program has been the well-known effort to develop high power, short wavelength laser drivers to create the conditions necessary for the fusion process. But the ICF Program has also been investigating, in collaboration with Lawrence Berkeley National Laboratory (LBNL), the potential of heavy-ion accelerators as possible drivers. The objectives of the Laboratory Directed Research and Development (LDRD) project described in this report have been to develop some of the enabling technologies necessary for this type of heavy-ion fusion (HIF) driver. In particular, to apply adaptive control to the problem of tailored acceleration and steering of a pulsed ion beam