Operating Modes of the Texas Petawatt Laser
The Texas Petawatt Laser offers users a selectable set of laser parameters available on target. There are four main categories for delivering light to multiple chambers (detailed below).
CW Alignment Light
This is a diode pumped, CW, Nd:YVO4 laser. The laser outputs around 4 W; however, due to losses in the system, 500 mW can be expected on target. At the user’s request, we can reduce the power level as well.
The CW laser is narrow band and centered at 1064 nm. It is injected into the laser chain before the 2nd Optical Parametric Amplifier stage. This light is collinear with the main laser pulse and is ideally suited for target alignment as well as diagnostic commissioning.
Injection of the CW laser is straightforward. We can provide this class of light to the target chamber at any time, including between shots if requested.
Optical Parametric Amplification (OPA) Shots
The OPA section of the laser typically amplifies the seed to around 500 mJ. The user can request OPA on target. At target, one can expect 100 mJ and compressed to 135 fs. This pulse is broadband (25 nm). The user can request OPA shots on target anywhere from single shot to 2.5 Hz continuously.
This class of light also can be delivered to either target chamber at any time, including in between shots.
Rod Shots
Upon request, rod shots can be delivered to target. The maximum energy that can be delivered to target is 7 J, compressed to 170 fs. If requested, rod shot energies could be reduced and pulse durations stretched. This subsystem operates single shot with a shot available every 15 minutes. The maximum shot count for a Rod Shot-only run would be 30 shots per day.
System Shots
System Shots are our full-energy shots, which deliver up to 1 PW of peak power to the target. The maximum energy delivered to target is 140 J compressed to 140 fs. The user can request shots down to 50 J. Additionally, if requested, the pulse duration can be stretched to the ps range. The shot rate for System Shot is one shot every hour. The maximum daily shot count is seven shots.
Comparison Table
The following table describes the four main classes of laser light and focusing geometries available to the user:
| CW | OPA | Rod Shots | System Shots | |
| Rep Rate | CW | Single Shot to 2.5 Hz | Every 15 minutes | Once an hour |
| Energy/Power on Target | 500 mW | 100 mJ | 7 J | Up to 140 J |
| Spot Size at TC1 | 5 µm | 5 µm | 5 µm | 5 µm |
| Spot Size at TC2 | 100 µm | 100 µm | 100 µm | 100 µm |
| Pulse Duration | N/A | 135 fs | 140 fs | 140 fs |
| Total # of Shots/Day | N/A | N/A | 30 | 7 |