COMET Capacitively Coupled Plasma(CCP) Diagnostic

March 29, 2024

• CCPs are simple, low impurity plasmas commonly used for processing. EEDF influences the rate of reactions and collisions, impacting species generation and processing parameters
• EEDF varies over the course of one RF cycle (74 ns period in 13.56 MHz supply)
• ns resolution time resolved Langmuir probe used to measure electron density and EEDF throughout the RF cycle.

This work uses a time-resolved Langmuir probe to measure the electron energy distribution function (EEDF) in a capacitively-coupled parallel-plate (CCP) plasma reactor. The EEDF completely determines the plasma chemistry in a low-temperature plasma, and that is why it is so important to obtain. By seeing how the EEDF changes throughout an RF cycle, both as a function of time and position, one then knows the extent by which altering the RF waveform can affect the energy of the electrons. Often industry mixes RF frequencies to alter the plasma — particularly the ion energy distribution at the substrate. Here we add a second frequency in a systematic manner and examine the changes in the instantaneous EEDF. We also examine the turn on and turn off times of the RF generator itself. Specialized circuits were designed for this work to ensure high frequency fidelity so digitization at 1.5 GHz is possible and accurate. A set of experiments were conducted to show how only altering circuit parameters affect the results, and steps were taken to eliminate those effects. Spatial variations of the resulting EEDFs were investigated, especially near the edge of the CCP reactor, to see which aspects change the most with radius.

Congratulations Dr. Steven Stemmley for his PhD!

March 28, 2024

On Tuesday March 26, 2024, Steven Stemmley held his final doctoral defense. His presentation on the “Liquid Lithium Loop Development For Open Surface Plasma Facing Components” earned him the completion of his PhD. Congratulations to Dr. Steven Stemmley for his PhD! Professor Dr. David. N. Ruzic was his advisor.

Congratulations Dr. Andrew Shone for his PhD!

March 28, 2024

On Monday March 25, 2024, Andrew Shone held his final doctoral defense. His presentation on the “Helium Retention Induced by In-Operando Lithium Evaporation” earned him the completion of his PhD. Congratulations to Dr. Andrew Shone for his PhD!

Graphene Growth in Atmospheric Plasma

March 27, 2024

Graphene is a 2D carbon structure with many useful properties including strength, conductivity, flexibility, and more. At IPI, graphene is grown in atmospheric pressure plasmas, breaking down methane (CH4), allowing the carbon radicals to recombine in a graphene-like structure.

Graphene is utilized in various applications, including battery technology and composite materials. Typical lithium-ion batteries can be altered to include graphene, which can improve battery life, increase the number of recharge cycles, improve conductivity, and even decrease the weight of the batteries. Because of the difficulty of growing graphene, understanding the growth mechanisms is vital to improving the conditions of the reactors, allowing for greater production rates and more graphene-like material, as opposed to amorphous carbon or carbon black. With an increase in graphene production and quality comes more efficient technologies, stronger materials, and increased battery life.

Graphene Growth in Atmospheric Plasma. SEM image of graphene-like carbon extracted directly from reactor

Flowing Lithium’s Adsorption and Release Experiment for Deuterium (FLARED)

March 27, 2024

Liquid lithium has been considered as a plasma facing component (PFC) as it can provide access to low recycling regimes due to its gettering abilities. However, in a low recycling regime, lithium is not only collecting impurity species, but also tritium. It is necessary to recover this tritium due to inventory and cost constraints. The purpose of Flowing Lithium’s Adsorption and Release Experiment for Deuterium (FLARED) is to investigate the uptake and transport of hydrogenic species.

The FLARED project adds an ECR plasma source to the Actively Pumped Open-surface Lithium Loop (APOLLO). This source will generate a Deuterium plasma, creating a flux of deuterium ions and radicals to the flowing liquid lithium Plasma Facing Component (PFC) installed in APOLLO. Through an array of plasma and neutral diagnostics and careful characterization the uptake of deuterium into the lithium can be measured. The Hydrogen Desorption Experiment (HyDE) distillation column will be installed downstream of the lithium PFC. This will allow for thermal treatments of deuterated lithium to separate the deuterium from the lithium. A differentially pumped RGA will be installed at the top of the column to measure the recapture rate of deuterium allowing for a balance of the ‘fuel’ within the system to be determined.  This work is sponsored by Tokomak Energy inc.

CPMI and IPI graduate students will present their research

March 20, 2024

CPMI and IPI graduate students will present the posters in the Department of Nuclear, Plasma, and Radiological Engineering at the University of Illinois at Urbana-Champaign on March 22, 2024 at 4pm. They will either highlight a research project or provide a summary of all the research group’s activities. They will present “Fusion Liquid Metal Research”, “The Illinois Plasma Institute: Graphene, Radical Probes, EUV, and More”, and “Center for Plasma Material Interactions: Plasma Processing and Diagnostics”.

CPMI Researchers will be part of a landmark program

June 9, 2023

The researchers of Center for Plasma Material Interactions (CPMI) at the University of Illinois at Urbana-Champaign (UIUC) will be part of a landmark program announced by the Department of Energy to support private companies in bringing fusion energy toward technical and commercial viability. As part of the DOE’s multimillion-dollar Milestone-Based Fusion Development Program, selected companies will team with U.S. national laboratories, universities, and others to address major technical and commercialization milestones for the successful design of a fusion pilot plant. Tokamak Energy Inc—the West Virginia-based U.S. subsidiary of British company Tokamak Energy Ltd and a longtime partner of the U of I—has been selected by the U.S. Department of Energy (DOE) for an award as part of its bold decadal vision for delivering commercial fusion. Research Associate Professor Dr. Andruczyk and Professor Dr. David Ruzic are the principal investigators on the NPRE portion of the project at UIUC.

Looking for a new Postdoc

June 8, 2023

The Center for Plasma Material Interactions (CPMI) at the University of Illinois at Urbana-Champaign is looking for a new Postdoctoral Research Associate level, who will work on research areas relevant to plasma material interactions for several industrial applications. In particular, we are looking for expertise in the field of Tokamak and Stellarator Operation, and Liquid Lithium/Metals as well as Chemistry and High-Power Impulse Magnetron Sputtering (HiPIMS). The hired postdocs are expected to closely work with Research Associate Professor Dr. Daniel Andruczyk and Professor Dr David Ruzic in managing research activities in the lab and conducting experiments while assisting students with research. Contact: Prof. Daniel Andruczyk ( and Prof. David Ruzic (