Guiding of relativistically intense laser beams in preformed plasma channels is discussed for development of GeV-class laser accelerators. Experiments using a channel guided laser wakefield accelerator (LWFA) at LBNL have demonstrated that near mono-energetic 100 MeV-class electron beams can be produced with a 10 TW laser system. Analysis, aided by particle-in-cell simulations, as well as experimentswith various plasma lengths and densities, indicate that tailoring the length of the accelerator, together with loading of the accelerating structure with beam, is the key to production of mono-energetic electron beams. Increasing the energy towards a GeV and beyond will require reducing the plasma density and design criteria are discussed for an optimized accelerator module. The current progress and future directions are summarized through comparison with conventional accelerators, highlighting the unique short term prospects for intense radiation sources based on laser-driven plasma accelerators.

Accelerator optimization requires detailed study of many parameters, indicating the need for remote control and automated data acquisition systems. A control and data acquisition system based on a network of commodity PCs and applications with standards based inter-application communication is being built for the l'OASIS accelerator facility. This system allows synchronous acquisition of data at high (> 1 Hz) rates and remote control of the accelerator at low cost, allowing detailed study of the acceleration process.

Laser wakefield accelerators produce accelerating gradients up to hundreds of GeV/m, and recently demonstrated 1-10 MeV energy spread at energies up to 1 GeV using electrons self-trapped from the plasma. Controlled injection and staging may further improve beam quality by circumventing tradeoffs between energy, stability, and energy spread/emittance. We present experiments demonstrating production of a stable electron beam near 1 MeV with hundred-keV level energy spread and central energy stability by using the plasma density profile to control selfinjection, and supporting simulations. Simulations indicate that such beams can be post accelerated to high energies,potentially reducing momentum spread in laser acceleratorsby 100-fold or more.

A GeV-class laser-driven plasma-based wakefield accelerator has been realized at the Lawrence Berkeley National Laboratory (LBNL). The device consists of the 40TW high repetition rate Ti:sapphire LOASIS laser system at LBNL and a gas-filled capillary discharge waveguide developed at Oxford University. The operation of the capillary discharge guided laser plasma wakefield accelerator with a capillaryof 225 mu m diameter and 33 mm in length was analyzed in detail. The input intensity dependence suggests that excessive self-injection causes increased beam loading leading to broadband lower energy electron beam generation. The trigger versus laser arrival timing dependence suggests that the plasma channel parameters can be tuned to reduce beam divergence.

The skewness of the envelope function of 20 - 100 femtosecond Ti:sapphire laser pulses has been controlled by appropriate choice of the higher order special phase coefficients, and used for optimization of a plasma wakefield electron accelerator.