1. Air Force Research Laboratory, Wright-Patterson Air Force Base, Ohio 45433, USA
2. Department of Physics and Astronomy, Brigham Young University, Provo, Utah 84602, USA
3. Department of Aerospace Engineering, Pennsylvania State University, University Park, Pennsylvania 16802, USA
4. Division of Engineering and Applied Science, California Institute of Technology, Pasadena, California 91125, USA
5. Advanced Propulsion and Power Laboratory, Virginia Tech, Blacksburg, Virginia 24061, USA