Plasma-based accelerator diagnostics based upon longitudinal interferometry with ultrashort optical pulses

Journal Article · Mon Apr 01 04:00:00 EST 1996 · IEEE Transactions on Plasma Science

DOI:https://doi.org/10.1109/27.509994· OSTI ID:264366

Siders, C W; Le Blanc, S P; Tajima, T; Downer, M C ^[1]; Babine, A; Stepanov, A; Sergeev, A ^[2]

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1. Univ. of Texas, Austin, TX (United States). Dept. of Physics
2. Inst. of Applied Physics, Nizhny Novgorod (Russian Federation)

All-optical ultrafast time-resolved plasma diagnostics of plasma-based accelerators (PBAs) are described, with emphasis on the laser Wakefield accelerator (LWFA). Specifically, the diagnostic techniques involve replacing the trailing particle bunch in the LWFA with a trailing photon bunch: a weak ultrashort laser pulse. Since this photon pulse is derived directly from the intense pump pulse, practical difficulties such as synchronization and dephasing are eliminated. The interaction of the photon bunch with the plasma wake is essentially a simple time-domain shift in optical phase, which can produce both dc phase shifts and frequency blue/red-shifting of the probe pulse spectrum. These phase/frequency shifts are recorded in frequency domain interferograms, which are formally equivalent to time-domain holograms. Experimental results of longitudinal plasma density profiling are presented in which plasma density oscillations (Langmuir waves) in the wake of an intense (I{sub peak} {approximately} 3 {times} 10{sup 17} W/cm{sup 2}) laser pulse ({approximately}100 fs) were measured with ultrafast time resolution. Phase shifts consistent with large amplitude ({approximately}80%) density oscillations at the electron plasma frequency were observed in a fully tunnel-ionized He plasma, corresponding to longitudinal electric fields of {approximately}10 GV/m. Strong radial ponderomotive forces enhance the density oscillations. Finally, proposed single-shot schemes for simultaneous transverse and longitudinal profiling are discussed.

• DOE Contract Number: FG05-92ER40739
• OSTI ID: 264366
• Journal Information: IEEE Transactions on Plasma Science, Journal Name: IEEE Transactions on Plasma Science Journal Issue: 2 Vol. 24; ISSN ITPSBD; ISSN 0093-3813
• Country of Publication: United States
• Language: English

Related Subjects

43 PARTICLE ACCELERATORS
EXPERIMENTAL DATA
HELIUM
INTERFEROMETRY
LASER RADIATION
PHOTON BEAMS
PLASMA DIAGNOSTICS
PLASMA WAVES
WAKEFIELD ACCELERATORS