ISSN:
1089-7623
Source:
AIP Digital Archive
Topics:
Physics
,
Electrical Engineering, Measurement and Control Technology
Notes:
We have measured time-resolved visible spectra emitted from a plasma formed when the output from a dye laser irradiates solid lithium. Such a plasma has potential as a source of lithium ions for ion-driven inertial confinement fusion, and it also provides a useful source for developing diagnostics. The laser delivered 0.5 J onto a 2–7-mm-diam spot, with a 900-ns pulse length. Experiments were performed with the wavelength tuned to the Li i 2s–2p resonance line at 6708 A(ring) and off resonance at 6728 A(ring). The target was a 500–1000-A(ring)-thick Li film, vacuum evaporated in situ onto a substrate. The light from the plasma was coupled into the entrance slit of a 1-m Czerny–Turner spectrograph, and the output from the spectrograph was focused onto the input slit of a streak camera. The electron density was obtained from Stark-broadened widths of Li i 2p–4d, 2p–5d, and 2p–4s, and H i 2p–4d. An irradiance of 2×106 W/cm2 at 6708 A(ring) resulted in a peak electron density of 3.9×1017 cm−3. The density decreased at lower irradiance, with an intensity threshold of 5×105 W/cm2 for producing an ionized plasma. The threshold for producing a plasma was higher with the laser tuned off resonance, although high-density lithium plasmas could still be formed at relatively low laser irradiance.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.1139695
Permalink
