NASA Goddard Space Flight Center
June 1, 2020 – August 7, 2020
Goals of your project/s:
During my internship, I worked on two projects of the EXCLAIM mission. The first project I worked on was simulating the magnetic shielding of the instrument inside a magnetic field. The goal of this project was to determine the shielding factor of the magnetic shielding. The second project was the thermal modeling/designing of a thermal strap for the Helmholtz coil experiment. The Helmholtz coil experiment will allow the EXCLAIM team to determine if the magnetic field vortex pinning is occurring in the superconducting films of the detector. The experiment requires the detector test package to be heated above the transition temperature of the aluminum of the MKIDs and then be cooled back down to the base temperature of 100 mK. The goal of my research/design was to design a thermal strap that could heat the detector test package above the transition temperature without affecting the temperature of the cooling element and then cool the package down to near 100 mK within one hour.
Describe what you did during the internship.
For the magnetic shield simulations, I used ANSYS Maxwell to simulate the magnetic shielding inside a magnetic field in the X, Z, and Axial (Y) directions and with frequencies between 0.1-60 Hz. Although the instrument will not experience fields oriented along a single axis, the field in any direction can be decomposed into X, Z, and Axial components, so we can determine how the shielding will perform in any direction. For the thermal modeling project, I used Python to solve thermodynamic equations to find the strap dimensions required in order to not exceed the power of the cooling element, the time constant of the strap, and the cool time.
Did you achieve your goals? What were the results and conclusions?
I achieved both of my project goals. My magnetic field simulations showed that the shielding performs the worst when the field is in the axial direction and at low frequencies. The lowest frequency I tested was 0.1 Hz, for a field in the Axial direction at this frequency, the magnetic shield had a shielding factor of 2290. My analysis of the thermal strap showed that the thermal strap needs to be made of 23-27 AWG copper wire in order to not exceed the maximum cooling power. The time constant of the strap is within a range of 1.22-1.36 minutes. The range of wire gauges and time constants is due to uncertainty in the purity of the copper. However, the variation in the time constants is too small to make a significant difference in the cool time, and the cool time of each purity tested was the same at around 10 minutes to cool to within 1 mK of the base temperature (100 mK). This thermal strap design will be implemented in the Helmholtz coil experiment to determine if vortex pinning is occurring in the superconducting films of the MKIDs as well as permitting the determination if a shielding factor of 2290 is sufficient to shield the MKIDs from Earth’s magnetic field and any magnetic fields produced by other elements of the instrument.
Describe positive lessons learned from this experience:
This summer program has been an excellent experience for me. I learned lots of new physics, specifically thermal physics. In addition to the physics I learned, I also learned how to use several new software programs, such as SolidWorks and ANSYS Maxwell. This experience and knowledge add to my overall body of knowledge in the field and will enhance my qualifications as a research scientist as my career advances. Emily, Eric, and Tom were very helpful, always willing to provide a helping hand or needed direction. It was great being able to work with and getting to know them from a distance. I am glad and grateful that NASA went forward with the internship in the face of the Covid-19 limitations.
Describe negative lessons learned from this experience:
The issues of the pandemic and Covid-19 and its effect on all aspects of our lives cannot be understated. The internship program with the Goddard Space Flight Center is no exception. I was excited to have the opportunity to join the EXCLAIM team at NASA this summer. While I was not certain what to expect in the face of Covid-19 adjustments, I quickly learned that remote/distance interactions between mentor and intern and between and among team members are different than classes. The interactions between people tended to be limited to the task at hand and did not permit a deeper personal interaction. I also learned that not being together tends to accentuate anything negative in terms of its impact. As an example, for me, my computer arrived without all of the proper software installed. It took us some time to get it all figured out and configured properly. I imagine that had I been on-site, I could have taken my computer to IT, and everything would have been figured out quickly. Also, my internship kind of “ruined” my personal laptop for me. The laptop NASA provided me is so much faster it spoiled me and makes my personal laptop feels like an old 286!