Introduction; Scientific Mission - Omega Volume VII–System Description Operation Manual

S-AD-M-005
Chapter 1: System Overview
1.0

Introduction

This chapter provides an overview of the OMEGA EP Laser System. The scientific mission of the
laser is described in Sec. 1.1. Section 1.2 provides an overview of the system configuration, and Sec. 1.3
provides a summary of the system specifications and laser energy requirements to meet the scientific
mission. Sections 1.4 and 1.5 describe the laser-sources and beamline configuration, including the grating
compressor and target chambers. Sections 1.6 and 1.7 describe the timing and optical alignment of the
system. Section 1.8 describes the laser diagnostics used to characterize the beams and Sec. 1.9 describes
the control system and the operations plan.
1.1

Scientific Mission

The primary experimental configurations possible using the four OMEGA EP beams are
summarized in Table 1.1. Two short-pulse beams can be co-propagated to either the OMEGA or
OMEGA EP target chambers for backlighting or fast-ignition experiments. Alternatively on OMEGA
EP, the short pulse beams can be propagated orthogonally for backlighting and sidelighting. Compressed
pulses from the upper of two pulse compressors may be propagated at full energy (2.6 kJ) with pulse
widths as short as 10 ps. B-integral constraints limit the pulse-width/pulse-energy trade-off of the pulse
emerging from the lower pulse compressor except when used for sidelighting applications in the OMEGA
EP target chamber. Alternatively, all four beams may be directed into the OMEGA EP chamber, with each
beam capable of being operated in long-pulse (UV) mode with independent temporal-pulse shapes and
pulse widths up to 10 ns. It is also possible to send two compressed pulses and two frequency-converted
pulses into the OMEGA EP target chamber on the same shot.
Five primary applications of the OMEGA EP laser beams that take advantage of this flexibility
are summarized below. Two applications of the OMEGA EP beams to the current OMEGA Facility
are described first, followed by three classes of experiments to be carried out in the OMEGA EP target
chamber. When all 60 beams of OMEGA are used to generate a symmetric implosion, the only way to
provide backlighting is to add additional beams to the system. The short-pulse, high-energy beams of
OMEGA EP are capable of backlighting implosions with sufficient brightness to overcome target self-
emission and are of a short enough duration to overcome motional blurring.
Short-pulse backlighting in the existing OMEGA target chamber
(a)
One or both of the compressed beams can be used to backlight targets in the OMEGA target
chamber with pulse-durations from 1 to 100 ps. As described in more detail in Sec. 1.1.1, high-intensity,
short-pulse lasers generate significant fluxes of high-energy x rays (>15 keV to ~1 MeV) and energetic
protons. Using the compressed beams as backlighters significantly enhances the options available and
allows a wider range of high-energy-density (HED) physics experiments to be performed on OMEGA
than previously possible. High-brightness backlighting sources with greatly improved temporal resolution
allow spherical inertial confinement fusion (ICF) implosions to be backlit. The two high-energy petawatt
Chapter 1
System Overview
January 2006—Page 1 of 35