Radiation from free electrons in a laser focus at 10^18 W/cm^2: modeling of photon yields and required focal conditions
| Autor: | Justin Peatross, Ryan Sandberg, Grayson Tarbox, Michael Ware, Eric Cunningham |
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| Rok vydání: | 2015 |
| Předmět: | |
| Zdroj: | Journal of the Optical Society of America B. 32:743 |
| ISSN: | 1520-8540 0740-3224 |
| DOI: | 10.1364/josab.32.000743 |
| Popis: | In support of an experiment designed to measure the strength of radiation scattered from low-density free electrons in an intense laser focus, we model a variety of physical parameters that impact the rate of scattered photons. We employ a classical model to characterize duration of electron exposure to high-intensity laser light in a situation where the electrons are driven by strong ponderomotive gradients. Free electrons are modeled as being donated by low-density helium, which undergoes strong-field ionization early in the pulse or during a prepulse. When exposed to relativistic intensities, free electrons experience a Lorentz drift that causes redshifting of the scattered 800 nm light. This redshift can be used as a signature to discern light scattered from the more intense regions of the focus. We characterize the focal volume of initial positions leading to significant redshifting, given a peak intensity of 2×1018 W/cm2. Under this scenario, the beam waist needs to be larger than several wavelengths for a pulse duration of 35 fs. We compute the rate of redshifted scattered photons from an ensemble of electrons distributed throughout the focus and relate the result to the scattered-photon rate of a single electron. We also estimate to what extent the ionization process may produce unwanted light in the redshifted spectral region. |
| Databáze: | OpenAIRE |
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