[技術分享] Plasma & Gas Jet Metrology
Straightforward and high-sensitivity diagnostic tool using high resolution phase imaging
The SID4 Density is a straightforward and extremely sensitive solution for neutral gas and plasma density measurement. It relies on a direct phase-shift measurement with our high-resolution wavefront sensor, the SID4-HR. The Phasics Density module addresses plasma and gas density measurement challenges for engineers and researchers working in plasma source design, laser-wake field acceleration (LWFA), and high-field sciences experiments.
Acknowledgments:
The works on plasma were pioneered at LOASIS, LBNL, which is now known as BELLA (Berkeley Lab Laser Accelerator) Center. The solution resulted from a fruitful collaboration between SourceLab and Phasics. SourceLab has brought its top-level know-how in laser-plasma interaction experiments and Phasics its strong expertise in phase measurement and analysis.
▽ Neutral gas particle density measurement setup
In this figure, the SID4 wavefront sensor is coupled with the R-Cube illumination module. The beam generated by the R-Cube travels through the optical system, reflects on a reference mirror, and is finally measured by the SID4. The test is performed in double pass. The wavefront aberrations measured are twice the aberration of the optical system. Thanks to a live feedback of the wavefront and Zernike polynomials, it is possible to optimize the optical system alignment in order to minimize the wavefront aberrations.
▽ Plasma electron density measurement setup
For plasma density measurement, the principle and implementation are similar as for the gas density. The only difference is that the probe beam must be synchronized with the drive laser. To do so, it is easy to use a small portion of the drive laser via a mirror leakage. A delay line can be used to study plasma dynamics and the probe can be frequency doubled to increase sensitivity.
Measurements Examples
Plasma density
Gas density
Plasma ionization front