Physics Research Projects 2022

Amina Ahmed

Advisor: David Schaffner

Magnetics Module for PlasmaPy

Data gathered from plasma physics experiments can be analyzed in a number of ways. The most efficient way to analyze raw plasma data is by running it through code which is equipped with the functionality to perform complex calculations. PlasmaPy is an opensource software ecosystem which provides a collection of the functionality needed by plasma physicists.

My project involves coding a module for the magnetics analysis. It includes adding functionality like computing magnetic fields, applying band pass filters, mean subtraction. The aim is for the magnetics module to be added to the PlasmaPy for others in the community to be able to use.

Maxwell Brenton

Advisor: David Schaffner

The Bryn Mawr Experiment (BMX) produces a confined plasma plume that can provide us with data on the behavior of plasma. One of the variables that is measured by the Bryn Mawr Experiment is the magnetic field. Using the cylindrical coordinate data of the magnetic field over time in the experiment, I calculated the change in angle between two magnetic field vectors over a time interval of one unit. I made a histogram of the angles that I collected in order to observe the distribution of those changes in angle. The distribution of the resulting histogram could be used to make further observations about the behavior of the plasma.

Queenie Jiang and Catherine Opsahl

Advisor: Michael Noel

Rubidium 85 atoms in a magneto-optical trap (MOT) can be excited into states with high principal quantum numbers n, or Rydberg states, using laser spectroscopy. Resonant energy exchange among these ultracold Rydberg atoms has been used in quantum computing, quantum simulation, and studies of dynamics in closed quantum systems. Prior studies of dipole-dipole interaction have focused on systems with few initial and final states. We have observed interactions among atoms excited to states within the Stark manifold using an electric field. The harmonic nature and large number of states in the manifold allow for rich dynamics in this energy exchange process.

Julia Moylan

Advisor: David Schaffner

Bryn Mawr Experiment

In the Bryn Mawr Experiment (BMX), a plasma plume is sent through a cylindrical chamber with probes arranged along the axial direction. As the plume travels, the magnetic field magnitude of the plasma varies. Looking at the intermittency in the magnitude of the magnetic field can indicate magnetic reconnection in the plasma. This is done using a histogram depicting a probability distribution function (PDF) of the incremental differences in magnetic field magnitude. Large tails on the Gaussian curve fit to this histogram could be an indication of the presence of magnetic reconnection. When paired with an analysis of the intermittency in the direction of the magnetic field, this analysis can provide insight into whether the plasma plumes have magnetic field lines that are connected to the plasma source. This is a question that also exists with the plasma solar wind from stars.

Amelia Stevens

Advisor: David Schaffner

Exponential Spectra of Magnetic Field Fluctuations in BMX

The fluctuating magnetic field within a flowing plasma on the Bryn Mawr Experiment is measured. The fluctuations in time series are decomposed using a Fast Fourier Transform (FFT) and plotted in semi-log form.” The slope of linear fits of the semi-log spectra map to an exponential function of the form e^(-omega*tau). It turns out that the inverse transform of this exponential function takes the form of a Lorentzian function of the form: tau^2/(t^2 + tau^2). The original fluctuations are compared to these Lorentzian structures to see if they are of similar size. If so, this suggests that the magnetic fluctuations are chaotic in origin.

Elizabeth Tompkins

Advisor: Michael Noel

Exciting Atoms to Rydberg States to Observe Long Range Dipole-Dipole Interaction

We can trap and cool rubidium atoms by manipulating wavelengths and frequencies of lasers as well as by applying electric and magnetic fields to the atoms. When the atoms are trapped, we then excite rubidium atoms to Rydberg state using different wavelength lasers. Once at these Rydberg states the atoms have principal quantum numbers that are very high (n=30) causing them to be weakly bound. This weakly bound state allows the atoms to exhibit exaggerated properties that result in long-range dipole-dipole interaction. This long-range interaction allows atoms to exchange energy and interact with one another even when separated by distances of several microns. We will be building the optical apparatus to produce a system that will conduct the trapping and excitation described above. We then can then observe and measure long-range dipole-dipole interaction between atoms.

Marie Wisz

Advisors: Kathryne Daniel and Karen Masters

The Impact of Spiral Pitch Angle on Radial Migration of Stars

As galaxies evolve over time, the orbits of their constituent stars change in size and shape. These two characteristics can be probed in tracer particle simulations of spiral galaxies via the initial and final measures of stellar populations that track the orbital eccentricity and angular momentum of individual stars over time. We investigate how these two characteristics of orbital patterns are influenced by spiral arm pitch angle with a focus on how stars move near the corotation resonance of a spiral pattern. For all pitch angles we find that there are changes in both orbital eccentricity and size for stars across a wide radial range of the galaxy, on different scales. The theoretical expectation is that only the orbital size will change at corotation. This project is in process and will examine trends in these orbital changes around corotation for several pitch angles. We aim to use MaNGA and Galaxy Zoo data to observationally probe related measures. In observed galaxies we cannot access orbital parameters directly so we will look at how the metallicity gradient of spiral galaxies changes with pitch angle. Since galaxies are expected to form with a significant metallicity gradient, a flattening of this gradient can be a useful probe of radial migration. This research will help to further understand the dynamical evolution of galaxies and the impact of spiral arms on radial migration.