Omega Volume VII-System Description, Руководство по эксплуатации

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Volume VII–System Description
OMEGA EP Operations Manual Page 10 of 35
A schematic diagram of the main components of a beamline is shown in Fig. 1.2. Each beamline
is “folded” into two levels: an upper level that includes a 7-disk booster amplifier and transport spatial
filter (TSF) and a lower level that forms a cavity between the cavity end mirror (CEM) to the south and
the deformable mirror (DM). The cavity includes an 11-disk main amplifier, a cavity spatial filter (CSF),
and a plasma electrode Pockels cell (PEPC). The DM corrects wavefront errors in the laser pulse that
originate from optical aberrations in the optics or from prompt-induced distortion of the laser disks
produced when the amplifiers fire. The PEPC is an electro-optical switch using polarization rotation to
trap the laser pulse in the cavity, providing an additional pass through the main amplifier resulting in
higher gain.
The seed laser pulse (generated in Laser Sources) is injected into the transport spatial filter via
a periscope. For short-pulse experiments in either target chamber, the seed pulses of Beams 1 and 2
are generated using optical parametric chirped-pulse amplification (OPCPA). The injected pulse passes
through the booster amplifier and is reflected off the fold mirror to the polarizer (POL1) and into the main
amplifier. The pulse makes either one or two round-trips through the cavity to gain the required energy,
then returns through the booster amplifier and TSF, and propagates to a switchyard. In the switchyard,
the beam is directed into the GCC for temporal-pulse compression or to the frequency-conversion
crystals (FCC’s) for the generation of long-pulse UV beams. A second polarizer (POL2 of Fig. 1.2) is
inserted between the PEPC and the CSF to prevent light reflected from the target from damaging the
main amplifier. Details of its use are explained in Sec. 1.5.
Figure 1.2
Optical components for the injection and amplification portions of an OMEGA EP beamline. Beamlines 3 and 4 do not
have short-pulse capability and therefore do not require POL2.
Injection lens
From
laser
sources
Up-collimator
Pointing/centering
mirrors
Vacuum window
Diagnostic
beamsplitter
To compressor
or FCC’s
Transport spatial filter
7-disk
booster amplifier
Fold
mirror
Cavity
end mirror
POL1
PEPC
Rejected
light
Cavity spatial filter
11-disk
main amplifier
Deformable
mirror
G5221cJ2
POL2*
45 m
23 m
*Used in beamlines 1 and 2 only