Plasma Dipole Oscillation Excited by Trapped Electrons Leading to Bursts of Coherent Radiation

TL;DR

This paper demonstrates a novel method to generate high-field plasma dipole oscillations using colliding laser pulses in plasma, resulting in coherent terahertz radiation, with potential applications in laboratory sources and astrophysics.

Contribution

It introduces a new technique to produce stable plasma dipole oscillations via trapped electrons in moving potential wells created by colliding lasers.

Findings

Generated several millijoules of terahertz radiation.

Achieved stable plasma dipole oscillations with high field strength.

Proposed a laboratory method for realizing plasma dipole oscillations.

Abstract

Plasma dipole oscillation (PDO) depicted as harmonic motion of a spatially localized block of electrons has, until now, been hypothetical. In practice, the plasma oscillation occurs always as a part of a plasma wave. Studies on radiation burst from plasmas have focused only on coupling of the plasma wave and electromagnetic wave. Here we show that a very-high-field PDO can be generated by the electrons trapped in a moving train of potential wells. The electrons riding on the potential train coherently construct a local dipole moment by charge separation. The subsequent PDO is found to persist stably until its energy is emitted entirely via coherent radiation. In our novel method, the moving potentials are provided by two slightly-detuned laser pulses colliding in a non-magnetized plasma. The radiated energy reaches several millijoules in the terahertz spectral region. The proposed method provides a way of realizing the PDO as a new radiation source in the laboratory. PDO as a mechanism of astrophysical radio-bursts is discussed.