A hemispherical Langmuir probe array detector for angular resolved measurements on droplet-based laser-produced...

Area of Science:

• Plasma Physics
• Materials Science
• Nanotechnology

Background:

• Laser-produced plasmas (LPPs) are critical for advanced applications like extreme ultraviolet (EUV) lithography.
• Understanding the dynamics of charged particles in LPPs is essential for optimizing source performance and debris mitigation.
• Droplet-based LPP sources present unique challenges due to their localized nature and potential for debris generation.

Purpose of the Study:

• To present a new diagnostic tool for characterizing laser-produced plasmas (LPPs).
• To enable temporally resolved, hemispherical mapping of ion and electron distributions around droplet-based LPP sources.
• To provide fundamental insights into plasma dynamics for enhancing debris mitigation techniques.

Main Methods:

• Development and implementation of a diagnostic system comprising a multiple array of six motorized Langmuir probes.
• Utilizing the system to measure charged particle dynamics, including angular and radial plasma charge distribution.
• Acquiring 2D mappings of ion kinetic energy distribution and estimating plasma density and electron temperature.

Main Results:

• Achieved the first-ever 2D mappings of ion kinetic energy distribution around a droplet plasma using a multi-probe array.
• Observed anisotropic expansion of ions in terms of kinetic energy and ion charge around the droplet target.
• Obtained initial estimations of plasma density and electron temperature from probe current signals.

Conclusions:

• The developed multi-Langmuir probe array is an effective diagnostic tool for LPPs, particularly droplet-based sources.
• The measurements provide crucial data on ion expansion dynamics, aiding in the development of improved debris mitigation strategies.
• This work advances the understanding of LPPs for EUV lithography and other applications requiring precise plasma control.