Helium atom line-intensity ratios as an integrated diagnostic tool for low-pressure and low-density plasmas

Atom and ion chemistry in low pressure hydrogen dc plasmas.

The chemical composition of a low-pressure hydrogen dc plasma produced in a hollow cathode discharge has been measured and modeled. The concentrations of H atoms and of H(+), H(2)(+) and H(3)(+) ions were determined with a combination of optical spectroscopic and mass spectrometric techniques, over the range of pressures (p approximately 0.008-0.2 m bar) investigated. The results were rationali...

Emission Line Spectra from Low-density Laboratory Plasmas

Estamos realizando mediciones en el laboratorio de las ĺıneas de emisión de iones importantes en la astrof́ısica, en el rango espectral de rayos-X de entre 1 y 400 Å , que cubrirán las misiones espaciales Chandra, XMM, Astro-E y EUVE. Los datos, obtenidos en un ambiente controlado a densidades similares a las de coronas estelares, son usados para verificar la exactitud y completez de códigos de ...

Low-temperature atom formation in ultracold neutral plasmas

Measurements of electron density and temperature in the H-1 heliac plasma by helium line intensity ratios.

Electron density and temperature distributions in the H-1 heliac plasma are measured using the helium line intensity ratio technique based on a collisional-radiative model. An inversion approach with minimum Fisher regularization is developed to reconstruct the ratios of the local emission radiances from detected line-integrated intensities. The electron density and temperature inferred from th...

A 300 GHz collective scattering diagnostic for low temperature plasmas.

A compact and portable 300 GHz collective scattering diagnostic employing a homodyne detection scheme has been constructed and installed on the hot helicon experiment (HELIX). Verification of the homodyne detection scheme was accomplished with a rotating grooved aluminum wheel to Doppler shift the interaction beam. The HELIX chamber geometry and collection optics allow measurement of scattering...