Dependence of ion charge-energy emission from Nd:YAG-laser-produced plasma on laser intensity in the 0.4 - 40 × 10 10 W/cm² range

We experimentally characterize the ionic emission, including the individual charge states Snz+ ( z = 1 , … , 8 ), from laser-produced tin plasma as a function of the intensity of the employed ns-pulsed laser. The plasma is generated in a vacuum from tin microdroplets (diameter ranging from 17 to 35 μm) using pulsed Nd:YAG laser light (laser wavelength λ = 1.064 μm) over a range of intensities (0.4- 40 × 10 10 W/cm2). We measure charge-state-resolved and integrated ion energy distributions at seven angular positions around the plasma using seven retarding field analyzers. We highlight peak features in both types of spectra and describe the dependence of their energies on laser intensity with power-law functions. The resulting power laws match those derived from plasma radiation hydrodynamics theory. The analytical scaling laws exhibit strong isotropy, while the ion energy spectra are highly anisotropic.</p

High repetition ultrafast electron bunches

Abstract only

Strongly anisotropic ion emission in the expansion of Nd:YAG-laser-produced plasma

We present results from a combined experimental and numerical simulation study of the anisotropy of the expansion of a laser-produced plasma into vacuum. Plasma is generated by nanosecond Nd:YAG laser pulse impact (laser wavelength λ = 1.064 μ m) onto tin microdroplets. Simultaneous measurements of ion kinetic energy distributions at seven angles with respect to the direction of the laser beam reveal strong anisotropic emission characteristics, in close agreement with the predictions of two-dimensional radiation-hydrodynamic simulations. Angle-resolved ion spectral measurements are further shown to provide an accurate prediction of the plasma propulsion of the laser-impacted droplet

Novel electron bunch creation towards ultrafast electron diffraction

Abstract only

Tin fluid dynamics driven by laser-produced plasmas relevant to EUV nanolithography

State-of-the-art nanolithography machines employ extreme ultraviolet (EUV) light to pattern nanometer-scale features on silicon wafers for the production of integrated circuits. This radiation is generated in a laser-produced plasma formed on tin microdroplet targets. In this contribution, we give an overview of our recent experimental and theoretical studies on the properties of tin plasmas driven by short-wavelength lasers and the subsequent tin fluid dynamics. First, we will present a comprehensive characterization of the properties of laser-produced tin plasmas driven by lasers with wavelengths in the 1-10 µm range. Second, we present absolutely calibrated, charge-state-resolved measurements of the ion kinetic energy distribution recorded under multiple detection angles. Through extensive radiation-hydrodynamic simulations of the plasma formation, growth and expansion, we demonstrate that a single-fluid approach accurately reproduces the angular dependence of the ion energy distribution. Moreover, we identify the origin of a high-energy peak in the distribution as a high-speed shell generated at early times in the expansion. Finally, we show that the time evolution of the droplet target morphology is entirely determined by the early-time plasma-driven pressure impulse on the droplet.</p

Polarization-dependent ponderomotive force in a standing wave

Abstract only

Generation of 2-micrometer wavelength laser-light to drive euv-emitting plasmas

A laser system based on three-wave mixing is used to generate laser-light at 2-micometer wavelength. This system is used for in-depth studies of the utility of 2-micrometer-driven sources of extreme ultraviolet (EUV) light in Nanolithography

Beam pulsing device for use in charged-particle microscopy

A charged-particle microscope comprising: - A charged-particle source, for producing a beam of charged particles that propagates along a particle-optical axis; - A sample holder, for holding and positioning a sample; - A charged-particle lens system, for directing said beam onto a sample held on the sample holder; - A detector, for detecting radiation emanating from the sample as a result of its interaction with the beam; - A beam pulsing device, for causing the beam to repeatedly switch on and off so as to produce a pulsed beam, wherein the beam pulsing device comprises a unitary resonant cavity disposed about said particle-optical axis and having an entrance aperture and an exit aperture for the beam, which resonant cavity is embodied to simultaneously produce a first oscillatory deflection of the beam at a first frequency in a first direction and a second oscillatory deflection of the beam at a second, different frequency in a second, different direction. The resonant cavity may have an elongated (e.g. rectangular or elliptical) cross-section, with a long axis parallel to said first direction and a short axis parallel to said second direction