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The recent and continuing development of powerful laser systems, which can now deliver light pulses containing a few Joules of energy in pulse durations of a few tens of femto seconds, has permitted the emergence of new approaches for generating energetic particle beams. By focusing these laser pulses onto matter, extremely large electric fields can be generated, reaching the TV/m level. Such fields are 10,000 times greater than those produced in the radio-frequency cavities of conventional accelerators. As a result, the distance over which particles extracted from the target can be accelerated GeV energy range is reduced to distances on the order of millimetres. A few years ago, several experiments have shown that laser-plasma accelerators can produce electron beam with maxwellian-like distribution [1], in 2004 high-quality electron beams, with quasi-mono energetic energy distributions at the 100 MeV level [2] and recently in the GeV range using a capillary discharge [3]. These experiments were performed by focusing a single ultra short and ultra intense laser pulse into an under dense plasma. More recently we produced a high quality electron beam using two counter-propagating
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