Characteristics of a Saturated 18.9 nm Tabletop Laser Operating at 5 Hz Repetition Rate
We report the characteristics of a saturated high repetition rate Ni-like Mo laser at 18.9 nm. This table-top soft x-ray laser was pumped at 5 Hz repetition rate by 8 ps, 1 J optical laser pulses impinging at grazing incidence into a pre-created Mo plasma. The variation of the laser output intensity as a function of the grazing incidence angle of the main pump beam is reported. The maximum laser intensity was observed for an angle of 20 degrees, at which we measured a small signal gain of 65 cm{sup -1} and a gain-length product gxl > 15. Spatial coherence measurements resulting from a Young's double slit interference experiment show the equivalent incoherent source diameter is about 11 {micro}m. The peak spectral brightness is estimated to be of the order of 1 x 10{sup 24} photons s{sup -1} mm{sup -2} mrad{sup -2} within 0.01% spectral bandwidth. This type of practical, small scale, high repetition soft x-ray laser is of interest for many applications. This acts to reduce the sensitivity of burst properties to metallicity. Only the first anomalous burst in one model produces nuclei as heavy as A = 100. For the present choice of nuclear physics and accretion rates, other bursts and models make chiefly nuclei with A {approx} 64. The amount of carbon remaining after hydrogen-helium bursts is typically {approx}< 1% by mass, and decreases further as the ashes are periodically heated by subsequent bursts. For M = 3.5 x 10{sup -10} M{sub {circle_dot}} yr{sup -1} and solar metallicity, bursts are ignited in a hydrogen-free helium layer. At the base of this layer, up to 90% of the helium has already burned to carbon prior to the unstable ignition of the helium shell. These helium-ignited bursts have (a) briefer, brighter light curves with shorter tails; (b) very rapid rise times (< 0.1 s); and (c) ashes lighter than the iron group.
- Research Organization:
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- Sponsoring Organization:
- US Department of Energy (US)
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 15015874
- Report Number(s):
- UCRL-JRNL-209395; TRN: US0501665
- Journal Information:
- IEEE Journal of Selected Topics in Quantum Electronics, Vol. 10, Issue 6; Other Information: Publication date December 1, 2004; PDF-FILE: 19 ; SIZE: 0.2 MBYTES; PBD: 10 Jan 2005; ISSN 1077-260X
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
70 PLASMA PHYSICS AND FUSION TECHNOLOGY
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
74 ATOMIC AND MOLECULAR PHYSICS
ASHES
BRIGHTNESS
CARBON
HELIUM
IGNITION
INCIDENCE ANGLE
IRON
LASERS
NUCLEAR PHYSICS
NUCLEI
PHOTONS
PLASMA
PULSE RISE TIME
SENSITIVITY
X-RAY LASERS