Leco Corporation

Kim Alvin Marshall

Peter Markel Willis

Ted J Casper

Joel C Mitchell

Carl D Warren

Steven J Rohaly

Sara K Casper

The embodiments of the invention include a method for controlling plasma conditions of a glow discharge system using the integrated electron (or ion) pulse area extracted from the total lamp current. The method of using an integrated electron/ion pulse area for controlling plasma conditions allows for controlled analysis of conductive, non-conductive and layered materials without the need for estimation of plasma voltages. The method allows for control of sputter rates and plasma emissions that cannot be achieved using other methods such as capacitive divider calculations where actual thicknesses and dielectric constants are not known or predefined.

System and method of determining effective glow discharge lamp current

An analytical combustion furnace has an input port for receiving a holder for an analytical sample. A purge block is coupled to the input port of the combustion furnace and has an input end for receiving the holder and a gas inlet and a gas outlet. A door selectively closes the input end of the purge block, and a pressurized seal is coupled between the purge block and the door. A source of purging gas is coupled to the gas inlet of the purge block for pressurizing the seal. The gas outlet of the purge block communicates with the seal to allow purging gas to escape the area of the seal. In one embodiment, a pressurized seal surrounds a push rod, which seal is pressurized by a purging gas to continuously purge the entry of the push rod into the purge block, thereby eliminating atmospheric contamination.

Pressurized gas purge seal for combustion furnace

A detection system for an atomic emission spectrometer includes a spherical convex diffraction grating having a radius of curvature which is one-half the radius of curvature of a pair of concave spherical mirrors. The diffraction grating and mirrors are positioned within a chamber such that their centers of curvature coincide at the focal plane to which a plurality of relatively small spaced-apart linear detectors are positioned on opposite sides of an emission entry slit to provide detection of alternate segments of a spectral band of wavelengths of interest.

Centered sphere spectrometer

This invention provides a gas atmosphere surrounding a seal between the face of a glow discharge lamp assembly and the sample surface to eliminate the possibility of the introduction of atmospheric gases into the glow discharge lamp. A groove concentric with the O-ring seal in the face of the glow discharge lamp is provided. This groove is supplied with gas slightly in excess of atmospheric pressure. This provides a gas blanket or jacket around the O-ring seal. Any leaks in the O-ring seal would draw the gas rather than atmospheric gases into the lamp. The incorporation of this modification is particularly important when a sample is being analyzed for elements which are also commonly present as atmospheric gases. The invention may be used on DC as well as RF glow discharge lamp assemblies.

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St. Joseph, MI, United States of America

Kim Alvin Marshall