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Cornell University

Laboratory of Plasma Studies

Understanding characteristics of plasmas, from microscopic to macroscopic scales

Research supporting MACH, Magnetic Acceleration Compression and Heating an NNSA Center of Excellence

The principal objective of our support for MACH is to improve the understanding of the physics of HED plasma through high quality experimental research, computer simulations, and theory. Our goals include advancing the capability of HED science in the United States and the training the next generation of HED research scientists for stockpile stewardship and other programs of importance to national security. We are interested in the application of magnetized HED plasmas to inertial fusion energy and intense radiation generation and the understanding of observed high energy astrophysical phenomena.

To achieve these objectives, we operate two pulsed power machines with a state-of-the-art suite of diagnostics. With these machines, our staff and graduate students at Cornell design and carry out world class magnetized HED plasma experimental research. This includes the study of x-pinches, gas-puff z pinches, plasma turbulence and novel z-pinch geometries. We also develop advanced computer simulations and analytic theory to help understand the experiments. Where necessary, we develop our own diagnostics that include Thomson scattering, visible and X-ray spectroscopy, Faraday rotation and Zeemann splitting for measuring magnetic fields and an imaging refractrometer for observing plasma turbulence.

Because of the extensive pulsed power and diagnostic capabilities at Cornell, time in our laboratory is made available to the other MACH Center partners for their experimental and computational work.

Laboratory Astrophysical Plasma Jets

We have studied two types of plasma jets.  The first, precursor jets, are basically hydrodynamic in nature and formed from ablating radial foils with and without an applied axial magnetic field.  With an applied magnetic field, the jets and ablated plasma above the foil were observed to rotate.  These jets were used to study the early time jet formation and propagated for only a few cm so had little relevance to astrophysical jets.  However, they are very reproducible and provide an excellent testbed for developing our Thomson scattering and other diagnosticsThe second jets are not formed from radial foil ablated plasma but from azimuthally symmetric ionized gas puff injection along magnetic field lines that have radial and axial components.  These jets are initiated later in the formation process than the precursor jets. Combined with the azimuthal magnetic field generated by the current driven by the pulse power generator, a helical magmatic field is imbedded in these magnetized jets. As a result, these jets self-assemble into a stable configuration characterized by magnetic field lines and force-free current flows following double helix paths inside the jet.  These jets have been observed in the laboratory to propagate several cm and appear to have many of the properties of astrophysical jets formed by black holes or collapsing stars and will be the subject of further investigation.

Power Flow Problems in Pulsed Power Machines

These studies investigate the behavior of realistic (multi-use) electrodes in the power flow of next generation pulsed power systems where materials will be subject to intense current densities, electric fields and radiation effects. This is a new program for LPS with more input on this Web Site as this study progresses.

Laser Propagation through Turbulent Plasma

This is also a new program for LPS and will investigate how laser beams propagate through highly perturbed/turbulent plasmas and hypersonic boundary layers.  This study will provide new, quantitative information for laser-based communication systems and potential laser-based early warning defense systems. An imaging reflectometry system is used to provide direct measurements of the effects of any small-scale disturbances of a plasma flow on a propagating beam. This is supplemented with Thomson scattering based measurements of density and velocity fluctuations from widening of the ion acoustic and electron plasma wave spectra alongside measurements of the bulk temperature, density, velocity and ionization state of the plasma.

Ultra-intense laser-plasma interactions for inertial fusion energy and advanced accelerators

Investigations of the interactions of ultra-intense laser pulses with gaseous and solid-density plasmas – theoretically, experimentally, and computationally – form another major research thrust of LPS funded by the National Science Foundation, Department of Energy, Office of Naval Research, and the Air Force Office of Scientific Research. Present research concentrates on the following areas:

  1. Laser-plasma accelerators of electrons, with applications to x-ray generation, development of future compact lepton colliders, and the development of medically-relevant compact accelerators for Very High Energy Electron (VHEE) radiation therapy.
  2. Interactions of petawatt-scale ultra-short laser pulses with solid-density targets and ion acceleration, with applications to Ion Fast Ignition of fusion capsules, ion-driven inertial fusion energy, and compact accelerators for ion-based cancer therapy.
  3. Interaction of laser pulses with nanostructured targets that result in the generation of highly-localized dense electron-hole plasmas, with applications to high-harmonics generation in solids, laser nano-machining, and the development of exotic targets for x-ray generation and ion acceleration.

Computational work in these areas is carried out using first-principles massively-parallel particle-in-cell (PIC) numerical codes: home-developed and open-access. Simulations are carried out on a number of high-performance computing platforms, including Lonestar and Stampede supercomputers at UT-Austin’s Advanced Computing Center. Experimental efforts take advantage of our proximity to several laser user facilities, including Brookhaven National Lab on Long Island, ALLS facility in Montreal, and Laboratory for Laser Energetics in Rochester.