The Use of Spider Silk to Support ICF Targets: Research by Mark Bonino

 When looking for someone doing physics research that I find interesting, I didn’t have to search very far! My father, Mark Bonino, is the target production manager, and is in charge of a group of assembly technicians who build 2600 targets each year at the University of Rochester Laboratory for Laser Energetics. Besides that, he does metrology and characterization using SEM, AFM and optical microscopy. He received a Bachelor of Science degree in Physics from St. John Fisher College in 1994, began working full time at the University of Rochester Laboratory for Laser Energetics in 1995, and completed his part time graduate studies in Materials Science in 2003. 

 

In general, Laser Lab employees support experiments in nuclear fusion (using the OMEGA Laser system – a system as big as a football field!) in order to find alternative energy sources. As interesting as this whole process is, I wanted to instead highlight a specific part of it using the research Mark did as he was working towards his Master’s degree - it more closely relates to what we have been talking about in class!

 

Mark focused his research on the implementation of spider silk to support direct-drive inertial confinement fusion (ICF) targets used in the OMEGA laser system, specifically because of the silk’s physical properties like stiffness, elasticity, tensile strength, and energy to break. The elastic properties of the silk are helpful when it comes to this application, because the capsule needs to remain stationary while at cryogenic temperatures before it is shot.

 

Looking specifically at the strength of the silk, tensile tests were done where samples were placed between two grips and pulled by a crosshead. This is where our class work relates, as Hooke’s law directly relates to this test (F_s = -kx)! The modulus of elasticity is analogous to the spring constant (k), F is the force applied, and x is the displacement. As we have learned, there is a linear relationship between the applied force and displacement, but Hooke’s law only works for small deformations. Large deformations leads to a non-linear relationship, and the law no longer applies. The point where the slope changes from linearity is called the yield point. It is here that the material is being strained beyond its elastic region, and any deformation after this point will not allow the sample to return to its original length. From the tensile test, three regions were identified: (1) the elastic region, (2) the inelastic region, and (3) the region after maximum loading. In the elastic region, the data follows a linear curve defined by Hooke's law.  

 

It’s so interesting to understand a part of the research that I have heard about for years on end, and exciting to see some of the concepts we have learned about in our class being applied to upper-level research in the field of Physics!

 

If anyone is interested in learning more about this materials science research, Mark’s thesis is linked below.

 

https://www.lle.rochester.edu/media/publications/documents/theses/Bonino.pdf