An atomic hydrogen etching sensor for H₂ plasma diagnostics.

Area of Science:

• Plasma Physics
• Materials Science

Background:

• Accurate measurement of atomic hydrogen flux is crucial for understanding and controlling plasma processes.
• Existing methods for atomic hydrogen detection can be complex or lack selectivity.

Purpose of the Study:

• To introduce and validate a novel, simple, and selective technique for measuring atomic hydrogen flux in hydrogen plasma environments.
• To demonstrate the effectiveness of a novel sensor design in suppressing ion interference.

Main Methods:

• Utilizing the etching rate of an amorphous carbon film as a direct measure of atomic hydrogen flux.
• Employing a specially designed "chimney" with a bend to neutralize ions through wall collisions.
• Fabricating the chimney from Macor, a material with low catalytic activity to preserve atomic hydrogen.
• Deploying the sensor in a radio frequency inductively coupled hydrogen plasma at low pressures (1-10 Pa).

Main Results:

• The technique successfully measures atomic hydrogen fluxes in the range of 10^19 to 10^21 m^-2 s^-1.
• Measurements obtained using the carbon etching sensor show agreement within a factor of 4 with heat flux sensors and vacuum ultraviolet absorption spectroscopy.
• The "chimney" design effectively suppresses ion flux, ensuring that the measured etch rate is dominated by atomic hydrogen.

Conclusions:

• The developed amorphous carbon etching sensor provides a reliable and selective method for atomic hydrogen flux quantification in plasma.
• This technique offers a valuable tool for plasma diagnostics and process control in various applications.
• The sensor's simplicity and effectiveness make it suitable for deployment in diverse plasma environments.