Final published version
Research output: Contribution to Journal/Magazine › Journal article › peer-review
Research output: Contribution to Journal/Magazine › Journal article › peer-review
}
TY - JOUR
T1 - Scaling High-Order Harmonic Generation from Laser-Solid Interactions to Ultrahigh Intensity
AU - Dollar, F.
AU - Cummings, P.
AU - Chvykov, V.
AU - Willingale, L.
AU - Vargas, M.
AU - Yanovsky, V.
AU - Zulick, C.
AU - Maksimchuk, A.
AU - Thomas, A. G. R.
AU - Krushelnick, K.
PY - 2013/4/24
Y1 - 2013/4/24
N2 - Coherent x-ray beams with a subfemtosecond (<10(-15) s) pulse duration will enable measurements of fundamental atomic processes in a completely new regime. High-order harmonic generation (HOHG) using short pulse (<100 fs) infrared lasers focused to intensities surpassing 10(18) W cm(-2) onto a solid density plasma is a promising means of generating such short pulses. Critical to the relativistic oscillating mirror mechanism is the steepness of the plasma density gradient at the reflection point, characterized by a scale length, which can strongly influence the harmonic generation mechanism. It is shown that for intensities in excess of 10(21) W cm(-2) an optimum density ramp scale length exists that balances an increase in efficiency with a growth of parametric plasma wave instabilities. We show that for these higher intensities the optimal scale length is c/omega(0), for which a variety of HOHG properties are optimized, including total conversion efficiency, HOHG divergence, and their power law scaling. Particle-in-cell simulations show striking evidence of the HOHG loss mechanism through parametric instabilities and relativistic self-phase modulation, which affect the produced spectra and conversion efficiency. DOI: 10.1103/PhysRevLett.110.175002
AB - Coherent x-ray beams with a subfemtosecond (<10(-15) s) pulse duration will enable measurements of fundamental atomic processes in a completely new regime. High-order harmonic generation (HOHG) using short pulse (<100 fs) infrared lasers focused to intensities surpassing 10(18) W cm(-2) onto a solid density plasma is a promising means of generating such short pulses. Critical to the relativistic oscillating mirror mechanism is the steepness of the plasma density gradient at the reflection point, characterized by a scale length, which can strongly influence the harmonic generation mechanism. It is shown that for intensities in excess of 10(21) W cm(-2) an optimum density ramp scale length exists that balances an increase in efficiency with a growth of parametric plasma wave instabilities. We show that for these higher intensities the optimal scale length is c/omega(0), for which a variety of HOHG properties are optimized, including total conversion efficiency, HOHG divergence, and their power law scaling. Particle-in-cell simulations show striking evidence of the HOHG loss mechanism through parametric instabilities and relativistic self-phase modulation, which affect the produced spectra and conversion efficiency. DOI: 10.1103/PhysRevLett.110.175002
KW - ELECTRON PARAMETRIC-INSTABILITIES
KW - PLASMA SURFACES
KW - OVERDENSE PLASMA
KW - X-RAYS
KW - PULSE
KW - TARGETS
KW - EMISSION
KW - DRIVEN
KW - LENGTH
KW - LIGHT
U2 - 10.1103/PhysRevLett.110.175002
DO - 10.1103/PhysRevLett.110.175002
M3 - Journal article
VL - 110
JO - Physical review letters
JF - Physical review letters
SN - 0031-9007
IS - 17
M1 - 175002
ER -