Ultrabroadband Microwave Radiation from Near and Mid-Infrared Laser Produced Plasmas in Air
Abstract
An ultrashort laser pulse focused in air creates a plasma that radiates broadband electromagnetic waves. We experimentally compare the generation of microwaves from plasmas produced with two different laser systems that operate in the near and mid-infrared regimes. Changing the laser wavelength increases the microwave power by 100 times, and changing the input pulse energy allows for tuning of the microwave frequency spectrum, which we absolutely calibrate over a range of 2-70 GHz. The variation of the spectrum with laser pulse energy confirms the existence of a distinct mechanism that generates microwave radiation from laser produced plasmas in gases. We propose that a radial diffusive expansion wave of the plasma electrons drives a longitudinal along the plasma surface whose amplitude varies with the total residual electron energy imparted by the laser field, and this longitudinal current produces the detected radiation.
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 10, 2020
- Accession Number
- AD1142690
Entities
People
- Adrian Lucero
- Alexander C Englesbe
- Andreas Schmitt-Sody
- D. Gordon
- Daniel Woodbury
- Dogeun Jang
- Howard Milchberg
- Jennifer Elle
- Ki-Yong Kim
- Remington Reid
- Robert E. Schwartz
- Ryan Phillips
- Serge Kalmykov
- Travis Garrett
Organizations
- Air Force Research Laboratory
- Leidos
- United States Naval Research Laboratory
- University of Maryland