Bi-Plasma Interactions on Femtosecond Time-Scales

关键词: DECAY;    ELECTROMAGNETIC FIELDS;    FLUORESCENCE;    LASERS;    PHYSICS;    PLASMA;    POLARIZATION;    PRODUCTION;    RADIATIONS;    TIME DELAY;    TRANSPORT Other;   

DOI  :  10.2172/1017214
RP-ID  :  SLAC-TN-11-015
PID  :  OSTI ID: 1017214
Others  :  TRN: US201113%%688

学科分类：物理（综合）

美国|英语

来源: SciTech Connect

【 摘 要 】

Ultrafast THz radiation has important applications in materials science studies, such as characterizing transport properties, studying the vibrational response of materials, and in recent years, controlling materials and elucidating their response in intense electromagnetic fields. THz fields can be generated in a lab setting using various plasma-based techniques. This study seeks to examine the interaction of two plasmas in order to better understand the fundamental physics associated with femtosecond filamentation processes and to achieve more efficient THz generation in a lab setting. The intensity of fluorescence in the region of overlap was measured as a function of polarization, power, and relative time delay of the two plasma-generating laser beams. Results of time dependent intensity studies indicate strikingly similar behaviors across polarizations and power levels; a sudden intensity spike was observed at time-zero, followed by a secondary maxima and subsequent decay to the initial plasma intensity. Dependence of the intensity on the power through either beam arm was also observed. Spectral studies of the enhanced emission were also carried out. Although this physical phenomenon is still not fully understood, future studies, including further spectral analysis of the fluorescence overlap, could yield new insight into the ultrafast processes occurring at the intersection of femtosecond filaments, and would provide a better understanding of the mechanisms for enhanced THz production.