The upgraded pharos II laser system

The Pharos II laser system has recently been upgraded for ablative acceleration studies at the Naval Research Laboratory (NRL). The design was optimized to produce uniform illumination of millimeter-size targets at intensities between 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">13</sup> and 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">14</sup> W/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> in a multinanosecond pulse. Key elements of the design were the use of high-gain phosphate laser glass in disk amplifiers, and optimal relaying and beam shaping in the neat field. These design elements are discussed, as well as the overall performance of the completed system.