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Non-equilibrium Microwave Plasma for Efficient High Temperature Chemistry
Published on: August 1, 2017
Bright multi-keV harmonic generation from relativistically oscillating plasma surfaces
Physical Review Letters
|October 13, 2007
Summary
Researchers observed high-order X-ray harmonic radiation from petawatt laser interactions, showing efficient scaling up to a specific order. Beyond this, intensity-dependent efficiency rollover occurred, with highly directional emission.
Area of Science:
- Plasma Physics
- Laser-Matter Interactions
- X-ray Science
Background:
- Petawatt-class lasers enable extreme light-matter interactions.
- High-order harmonic generation (HHG) is a key process for X-ray production.
- Understanding efficiency scaling and emission characteristics is crucial for applications.
Purpose of the Study:
- To investigate X-ray harmonic radiation generated by petawatt laser-solid interactions.
- To characterize the efficiency scaling and emission properties at multi-keV energies.
- To identify the onset of intensity-dependent effects in HHG.
Main Methods:
- Utilized petawatt-class laser systems interacting with solid targets.
- Analyzed X-ray harmonic spectra to determine order and energy.
- Measured emission cone angles and efficiency scaling with harmonic order.
Main Results:
- Observed X-ray harmonic radiation extending to 3.3 Å (3.8 keV, order n>3200).
- Demonstrated relativistic limit efficiency scaling (η ∝ n⁻².⁵–n⁻³) at multi-keV energies.
- Identified an intensity-dependent efficiency rollover beyond a maximum order (nRO ∝ γ³).
Conclusions:
- Established efficient high-order harmonic generation up to n>3200 from petawatt lasers.
- Characterized the transition to intensity-dependent rollover, providing insights into emission physics.
- Confirmed coherent, highly directional X-ray emission (≈4° cone angle for >1 keV photons).
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