Effect of laser intensity on fast-electron-beam divergence in solid-density plasmas.
Metal foil targets were irradiated with 1 mum wavelength (lambda) laser pulses of 5 ps duration and focused intensities (I) of up to 4x10;{19} W cm;{-2}, giving values of both Ilambda;{2} and pulse duration comparable to those required for fast ignition inertial fusion. The divergence of the electrons accelerated into the target was determined from spatially resolved measurements of x-ray K_{alpha} emission and from transverse probing of the plasma formed on the back of the foils. Comparison of the divergence with other published data shows that it increases with Ilambda;{2} and is independent of pulse duration. Two-dimensional particle-in-cell simulations reproduce these results, indicating that it is a fundamental property of the laser-plasma interaction.
Green
J S
JS
Central Laser Facility, Rutherford Appleton Laboratory, Chilton, Oxon OX11 0QX, United Kingdom.
Ovchinnikov
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Evans
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Akli
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Azechi
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Beg
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Bellei
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Freeman
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Habara
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Heathcote
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Key
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King
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Lancaster
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Lopes
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MacKinnon
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Markey
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McPhee
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Najmudin
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Nilson
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Onofrei
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Stephens
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Takeda
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Tanaka
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Theobald
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Tanimoto
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Waugh
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Van Woerkom
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Woolsey
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Davies
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Norreys
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