Measuring the equations of state in a relaxed magnetohydrodynamic plasma." Physical Review 97.1, 011202(R).

We have explored the thermodynamics of compressed magnetized plasmas in laboratory experiments and we call these studies 'magnetothermodynamics'. The experiments are carried out in the Swarthmore Spheromak eXperiment device. In this device, a magnetized plasma source is located at one end and at the other end, a closed conducting can is installed. We generate parcels of magnetized plasma and observe their compression against the end wall of the conducting cylinder. The plasma parameters such as plasma density, temperature and magnetic field are measured during compression using HeNe laser interferometry, ion Doppler spectroscopy and a linearḂ probe array, respectively. To identify the instances of ion heating during compression, a PV diagram is constructed using measured density, temperature and a proxy for the volume of the magnetized plasma. Different equations of state are analysed to evaluate the adiabatic nature of the compressed plasma. A three-dimensional resistive magnetohydrodynamic code (NIMROD) is employed to simulate the twisted Taylor states and shows stagnation against the end wall of the closed conducting can. The simulation results are consistent to what we observe in our experiments.

Blood clots block proper blood flow in vessels and often lead to fatal health conditions such as cardiac ischemia and stroke, especially in an aging population. Because ultrasonic fields can cause cavitation of fluids, administration of ultrasound and microbubble contrast agents can induce intravascular thrombolysis (dissolution of blood clots). Quantitative and qualitative data were collected on how a porcine blood clot dissolves when exposed to Definity™ microbubbles and 1 MHz pulsed ultrasound. In addition, bubble dynamics in response to the measured ultrasonic wave field were modeled using a modified Gilmore equation. The results allowed us to optimize parameters and better understand the interaction of the clot fibrin structure and the movement of microbubbles through it. Advances in the understanding of sonothrombolysis can help transform its clinical application in patients efficiently, especially in instances where life depends on rapid dissolution of a thrombus.