Engineering topics

Yandow, A.

Publications and source records attributed to Yandow, A..

4 records

DOE OSTI2024

Above-threshold ionization at laser intensity greater than 10 20 W / cm 2

Here we present experimental observation of above-threshold ionization (ATI) electrons produced by ionization of the neon K shell in a laser field where intensity exceeds 10 20 W/cm 2 . An array of plastic scintillating calorimeter detectors was used to measure the high-energy electrons at four angles in the laser forward direction. Coarse energy resolution was obtained using aluminum filters of several thicknesses to block lower-energy electrons. A threshold intensity around 2×10 20 W/cm 2 is observed for production of energetic ATI electrons in the laser forward direction, with maximum electron energy exceeding 10 MeV. L-shell electrons with energies <1.4 MeV are scattered farther forward along the laser direction than expected. We present comparisons of the measured total electron energies to the predictions of Monte Carlo models employing the ADK-PPT ionization model and the Augst barrier suppression ionization model.

74 ATOMIC AND MOLECULAR PHYSICS↗

DOE OSTI2023

Multi-MeV Electrons from Above-Threshold Ionization of the Neon K-Shell

We present measurements of integrated electron energies produced by above-threshold ionization (ATI) of neon in a laser field with intensity exceeding 10 20 W/cm 2 . We observe electrons with energy exceeding 10 MeV ejected in the laser forward direction above a threshold intensity of 2 ×10 20 W/cm 2 . Here, we compare to ATI models using both tunneling (ADK-PPT) and barrier suppression ionization and observe the onset of ATI at a higher threshold intensity than predicted by these 15 models.

74 ATOMIC AND MOLECULAR PHYSICS↗

DOE OSTI2019

Direct laser ion acceleration and above-threshold ionization at intensities from 10 21 W/cm 2 to 3 × 10 23 W/cm 2

Calculations on the dynamics of ions and electrons in near-infrared laser fields at intensities up to 3 × 10 23 W/cm 2 are presented here. We explore the acceleration of ions in a laser focus by conservation of canonical momentum during ionization events and by the ponderomotive force in the f/1 focal geometry required to reach such intensity. At intensities exceeding 10 23 W/cm 2 , highly charged ions are expelled from the laser focus before they can interact with the laser pulse at peak intensity, decreasing the predicted ionization yields of deeply bound states. We consider the interaction of a tightly focused, f/1 laser pulse with krypton at an intensity of 3 × 10 23 W /cm 2 and a pulse duration of 140 fs.We find that the ions and electrons are accelerated to energies in excess of 2 MeV/nucleon and 1.4 GeV, respectively. Ponderomotive expulsion of the parent ions decreases the total number of ultrarelativistic above-threshold ionization electrons produced by tunneling ionization from the K-shell states of krypton but does not change their energy spectrum.

74 ATOMIC AND MOLECULAR PHYSICS↗

DOE OSTI2019

Beam distortion effects upon focusing an ultrashort petawatt laser pulse to greater than 10 22 W/cm 2

When an ultrashort laser pulse is tightly focused to a size approaching its central wavelength, the properties of the focused spot diverge from the diffraction-limited case. Here, we report on this change in behavior of a tightly focused petawatt-class laser beam by an $f/1$ off-axis parabolic mirror (OAPM). Considering the effects of residual aberration, the spatial profile of the near-field, and pointing error, we estimate the deviation in peak intensities of the focused spot from the ideal case. Here, we verify that the estimated peak intensity values are within an acceptable error range of the measured values. With the added uncertainties in target alignment, we extend the estimation to infer on-target peak intensities of ≥10 22 W/cm 2 for a target at the focal plane of this $f/1$ OAPM.

47 OTHER INSTRUMENTATION↗