LPS graduate students Jacob Banasek and Sophia Rocco attended a two-day International Workshop on Optical Thomson Scattering hosted by the University of Rochester at the Laboratory of Laser Energetics (LLE). Participants shared recent advancements in diagnostic development at their various institutions, the labs of which span a large range of interesting plasma conditions, from picosecond laser-produced plasmas to the nanosecond-scale pulsed-power plasmas at Cornell. Jacob and Sophia both presented talks on their work in developing the Thomson scattering diagnostic in use at Cornell (“Thomson scattering on Laboratory Plasma Jets to Study Current Polarity Effects” and “Thomson scattering as a tool for differentiating sources of spatial velocity distributions in gas-puff z-pinches,” respectively). The collective expertise in the room was incredible, and Cornell came away with some new perspectives and fresh ideas about how to approach both Thomson collection and analysis in improved ways.
Over the Summer Paul worked with Dr. Sander Lavine and Professor Bruce Kusse to design a capacitor bank. The capacitor bank will deliver strong axial magnetic fields via a Helmholtz coil during the plasma Z pinch. This effect can be used in multifarious experiments to explore different properties of plasma.
Paul used SOLIDWORKS to finish modeling the capacitor layout, current path, bank housing, and physical framing of the capacitor bank. Then explored circuit simulators which helped estimate the circuit’s transient response, aiding the diode selection process. The diode stack is necessary in order to stultify voltage reversal on the capacitors; any significant voltage reversal could damage or even destroy them. He then advised a main cable for the capacitor bank to conduct the pulse, and confirmed it could handle the high current and voltage at the given frequency of the circuit.
Currently, Paul is investigating the proposed snubber circuit and what components would be sufficient for its proper functioning.
Worked with Professor David Hammer and Dr. Billy Potter designing a two-color interferometer as a future upgrade to the interferometry diagnostic currently in COBRA.
This summer he has been working with Dr. Sander Levine and Professor Bruce Kusse investigating why PLIF is not consistent day to day and coming up with a solution to improve the reproducibility and accuracy of PLIF. This has led him to develop a new calibration method for calibrating gas puff data from PLIF.
PLIF data is used to understand the data that comes out of COBRA, so for COBRA to be accurate the PLIF data must be accurate.
Euan graduated from the University of Evansville (’19) and is at LPS this summer studying plasma spectroscopy in order to be able to perform visible light spectroscopy experiments, and assisting senior researchers and graduate students with their work in order to learn how to run experiments on COBRA. Euan will join Cornell as a graduate student Fall 2019.
Taking measurements of radiation spanning the millimeter-wave range up to the near infrared range. Making measurements of turbulent density fluctuations with a proposed Thomson scattering diagnostic which operates in the Bragg scattering limit.
This summer so far:
- Developed a 94 GHz microwave radiometer along with three infrared (IR) radiometers at 1100, 1310, and 1550 nm.
- Implemented these instruments on COBRA, with measurements taken for various plasma conditions (gas puff, single wire, gas puff + wire, varying gases)
What is planned for the rest of the summer:
- Understand the current set of measurements of COBRA plasmas.
- Determine whether a black body spectrum is apparent in the IR measurements. If so, temperatures can be derived.
- Further analyze the microwave measurements to derive the absolute intensity of the emissions – this will help (along with IR measurements) to determine the total energy expended into radiation the imploding plasma.
- Continue developing a collective Thomson scattering system, allowing for insight into how energy is expended into turbulence in an imploding gas puff plasma.
While at Weizmann Institute they worked with Marko Cvejić, Tal Queller and Dmitry Mikitchuk.to learn about their various research projects and techniques. Mainly focusing on getting hands-on experience with their Zeeman polarimetry technique and neutral gas interfromety. In addition, time was also spent discussing other spectroscopic interests of the lab.