Zane Harvey

CONSOL Energy

Summary form only given. We report observations that confirm the theoretical prediction1 that formation of a current-free double layer in a plasma expanding into a chamber of larger diameter is accompanied by an increase in ionization upstream of the double layer. The increased ionization is caused by electrons accelerated to the upstream side of t...

We report observations that confirm a theoretical prediction that formation of a current-free double layer in a plasma expanding into a chamber of larger diameter is accompanied by an increase in ionization upstream of the double layer. The theoretical model argues that the increased ionization is needed to balance the difference in diffusive losse...

We present ion velocity distribution function (IVDF) measurements obtained with a five grid retarding field energy analyzer (RFEA) and IVDF measurements obtained with laser induced fluorescence (LIF) for an expanding helicon plasma. The ion population consists of a background population and an energetic ion beam. When the RFEA measurements are corr...

We observe a threshold frequency for ion beam formation in expanding, low pressure, argon helicon plasma. Mutually consistent measurements of ion beam energy and density relative to the background ion density obtained with a retarding field energy analyzer and laser induced fluorescence indicate that a stable ion beam of 15 eV appears for source fr...

A four grid retarding field energy analyzer (RFEA), with a fifth grounded entrance grid, has been constructed based on published design criteria [Charles et al., Phys. Plasmas 7, 5232 (2000).]. A fast amplifier is used to sum the current collected by the suppressor grid and the collector current. Measurements of the ion velocity distribution functi...

A method of gas temperature determination in nitrogen or nitrogen doped discharges is presented. The method employs fits of numerically generated spectra of the 0-0, 1-0, and 2-0 bands of the first positive system (B ³Π_g→A ³Σ_u⁺) of nitrogen to experimental measurements. Excellent agreement betw...

We present a method of rotational and vibrational temperature estimation in nitrogen plasma by simulation of the emission spectrum of the first positive system (B ³Π_g→A ³Σ_u⁺) of nitrogen. The gas kinetic temperature, assumed to be in equilibrium with the rotational temperature, was obtained fro...

Summary form only given. We report preliminary results on the development of a helicon plasma source with variable activated nitrogen composition for plasma assisted molecular beam epitaxy of III/V-nitrides. The main idea is to alter the population of specific reactive nitrogen species in a helicon plasma source by modifying the electron energy dis...

Summary form only given. There is a need for moderate energy fluxes of metastable nitrogen molecules in the growth of thin films of GaN, a wide band gap semiconductor. A laser induced fluorescence technique (LIF) has been developed for the measurement of N2 (A3 u + S , v=4) relative population density and flow speed in a steady state, helicon disch...

We report on the gas temperature and the degree of dissociation in E, H, and W operating regimes of nitrogen helicon plasma. The gas temperature was inferred from the fit of synthetically generated spectra to the recorded emission spectra of the 2-0, 1-0, and 0-0 bands of the first positive system of nitrogen. The dissociation degree was inferred f...

A retarding field energy analyzer (RFEA) suitable for measurements in high density rf plasmas has been constructed and tested in two helicon plasma sources at West Virginia University. Similar RFEA's have been used to measure the acceleration of ions and the plasma potential in the double layers that spontaneously form in low pressure, expanding he...

A compact 300 GHz homodyne collective scattering system is being installed on the WVU helicon plasma source. The purpose of the system is to measure short wavelength electromagnetic waves at the edge of the plasma with the expectation of explaining the high RF absorption efficiency of helicon plasma sources.