[en] A novel type of ion source was designed and constructed for studies of chemical ionization processes, using low energy ions produced from inorganic gases in a high frequency flow discharge. Temperature and electron density profiles were measured in the downstream of the discharge region by cylindrical Langmuir- and orifice-probes. Typical plasma temperatures and densities are: Tsub(e)=2-3 eV; nsub(e)=(0.5-2.0)x10¹¹ cm^-3. (Auth.)

[en] Simple theory and basic plasma physics experiments are used to deduce scaling laws for ion source discharges. (author)

No abstract available

[en] When a metallic body is inserted inside plasma chamber it is always associated with sheath which depends on plasma and wall condition. The effect of sheath formed in the magnetic drift and magnetic field direction on cross field plasma transport has been investigated in a double Plasma device (DPD). The drifts exist inside the chamber in the transverse magnetic field (TMF) region in a direction perpendicular to both magnetic field direction and axis of the DPD chamber. The sheath are formed in the magnetic drift direction in the experimental chamber is due to the insertion of two metallic plates in these directions and in the magnetic field direction sheath is formed at the surface of the TMF channels. These metallic plates are inserted in order to obstruct the magnetic drift so that we can minimised the loss of plasma along drift direction and density in the target region is expected to increase due to the obstruction. It ultimately improves the negative ion formation parameters. The formation of sheath in the transverse magnetic field region is studied by applying electric field both parallel and antiparallel to drift direction. Data are acquired by Langmuir probe in source and target region of our chamber. (author)

No abstract available

[en] High-frequency oscillations (1-100 MHz) are drawing significant attention in the recent research of Hall thrusters. A diagnostic setup, consisting of single Langmuir probe, special shielded probe connector-positioner, and electronic impedance-matching circuit, was successfully built and calibrated. Through simultaneous high-frequency probing of the Hall-thruster plasma at multiple locations, high-frequency plasma waves have been successfully identified and characterized

[en] We present a novel plasma diagnostic for measuring local plasma density in reactive-gas plasmas, and depositing plasmas. The diagnostic uses a network analyzer to measure the LC resonance (LCR) frequency of a parallel plate capacitor with inductive leads. The location of the LCR (ω_R) in frequency space is then used as a measure of the plasma dielectric constant bold varepsilon_p between the plates. By properly constructing the LCR probe, ω_R can be tuned such that ω_R >> ω_ce, where ω_ce is the electron-cyclotron frequency. Thus, the probe can be used in plasmas with varying degrees of magnetization while avoiding complications introduced to bold varepsilon_p when ω is comparable to ω_ce. Density measurements from the LCR probe are compared with Langmuir probe measurements in an electron-beam generated plasma in which density varied from 10⁹ to 10¹¹ cm^-3. An axial magnetic field, typically used to confine the electron beam, was varied between 0 to 300 G. The LCR probe showed good agreement with a Langmuir probe across the entire range of magnetic fields.

[en] The details of the mechanical design and fabrication for a Langmuir Probe for the continuous monitoring of plasma density are given. The probe was designed for use as a diagnostic tool in the development of long pulse positive ion plasma sources for use on neutral beam systems. The essential design feature of this probe is the incorporation of two electrically isolated cooling water circuits which actively cool the probe tip and probe jacket. The electrical isolation is required to prevent drain currents from the probe body disturbing the measurement of the probe tip current and thereby the plasma density measurement. The successful realization of the design requires precision components and vacuum tight ceramic to refractory metal brazes. To date this design has successfully operated in steady-state in plasma densities up to 250 mA/cm² and surface heat fluxes of 25 W/cm²

[en] Large electrostatic potential variations in the form of sheaths and double layers (both stationary and moving) are studied in laboratory plasmas. Filament discharge plasmas are generated in a multidipole soup pot and a triple-plasma device where the electron density n/sub e/ is varied from 1 to 500 x 10⁷ cm^-3 and the electron temperature T/sub e/ approx. ] to 3 eV in argon and helium plasmas. Emitting, collecting and floating Langmuir probes are used to study the phenomena associated with large potential variations

[en] The basic equations and boundary conditions for the kinetic analysis of generalized Tonks-Langmuir systems (collisionless plasma systems enclosed in a finite volume of arbitrary shape) are formulated both in the quasineutral plasma limit and accounting for space charge. It is shown that the analysis of problems with various positive ion components can be reduced under very general conditions to the analysis of an equivalent one-component problem. This kinetic similarity is lost in fluid theory