Around the Lab
OMEGA EP Amplifier
June, 2003Amplifiers and their associated power conditioning units are the basic building blocks of any laser system. The energy required to perform ICF experiments is much greater than that in the initial beam. Amplifiers placed throughout the system incrementally increase the energy of each beam until it meets the requirements for experimental use.
Amplifiers work by “giving” more energy to the laser beam. The process of amplification begins in the Power Conditioning Units (PCUs). These units store electrical energy from a wall plug in a series of energy storage capacitors. When the amplifier is “fired”, an ignitron switch in the PCU connects these capacitors to a series of flash lamps inside the amplifier. These lamps (much larger versions of the ones in a photographic camera) emit a brief (~ 1 millisecond) pulse of intense white light. This intense white light is absorbed by the amplifier’s Neodymium-doped laser glass. It is the Neodymium (a rare-earth) in the laser glass which stores the white light’s energy and transfers it to the laser beam propagating through the laser glass.
As with many components of OMEGA EP, amplifiers that meet the system requirements are not produced commercially and must be designed in-house. This LLE-designed amplifier configuration is similar to amplifiers currently used in the 60-beam OMEGA Laser System. However, each OMEGA amplifier uses four laser disks, while the OMEGA EP prototype amplifier will contain a single disk. Ultimately, eleven of these modules will be used in the main amplifier and five will be used in the booster amplifier. Other requirements include a modular design (three major assemblies: the amplifier frame assembly, the disk frame assembly, and the pump module); water-cooling for glass components; the ability to take at least one shot every two hours (i.e., the optics must cool down within this time frame to prevent damage); the ability to accommodate a 40-cm-sq. laser beam, and maintenance similar to the existing OMEGA amplifiers.
Three power conditioning units for the OMEGA EP prototype amplifier. Each unit powers flash lamps on one side of one laser disk.
Close-up of one power conditioning unit showing the bus work necessary to drive six sets of flash lamps. The gray boxes are energy storage capacitors. The gold cylinder (middle right) contains the ignitron switch for the unit.
Prototype OMEGA EP amplifier in a test configuration. In the distance, a technician adjusts gain probes on an optical table. A plane retro mirror is shown in the foreground. Blue pendant cables deliver power to the flash lamps.
Residual glow on amplifier elements. The vertical lights on the left are from the flash lamps; on the right is the amplifier glass.
View of the throat of the amplifier. A current 60-beam OMEGA amplifier would fit inside of this model.
The amplifier in action.