Overview of the National Ignition Facility

Brereton, S.J.

doi:10.1097/hp.0b013e31828cf5cd

Cited by 3 publications

(3 citation statements)

References 4 publications

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“…Potassium Dihydrogen Phosphate (KDP) crystal is currently one of the important and irreplaceable optical components used in high power laser systems for inertial confinement fusion (ICF) research [ 1 , 2 , 3 ]. However, its laser damage resistance becomes the key factor that severely restricts the output performance of the lasers [ 4 ] and this is an urgent technological issue to be resolved in the engineering application.…”

Section: Introductionmentioning

confidence: 99%

Laser Induced Damage of Potassium Dihydrogen Phosphate (KDP) Optical Crystal Machined by Water Dissolution Ultra-Precision Polishing Method

et al. 2018

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Laser induced damage threshold (LIDT) is an important optical indicator for nonlinear Potassium Dihydrogen Phosphate (KDP) crystal used in high power laser systems. In this study, KDP optical crystals are initially machined with single point diamond turning (SPDT), followed by water dissolution ultra-precision polishing (WDUP) and then tested with 355 nm nanosecond pulsed-lasers. Power spectral density (PSD) analysis shows that WDUP process eliminates the laser-detrimental spatial frequencies band of micro-waviness on SPDT machined surface and consequently decreases its modulation effect on the laser beams. The laser test results show that LIDT of WDUP machined crystal improves and its stability has a significant increase by 72.1% compared with that of SPDT. Moreover, a subsequent ultrasonic assisted solvent cleaning process is suggested to have a positive effect on the laser performance of machined KDP crystal. Damage crater investigation indicates that the damage morphologies exhibit highly thermal explosion features of melted cores and brittle fractures of periphery material, which can be described with the classic thermal explosion model. The comparison result demonstrates that damage mechanisms for SPDT and WDUP machined crystal are the same and WDUP process reveals the real bulk laser resistance of KDP optical crystal by removing the micro-waviness and subsurface damage on SPDT machined surface. This improvement of WDUP method makes the LIDT more accurate and will be beneficial to the laser performance of KDP crystal.

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Section: Introductionmentioning

confidence: 99%

Laser Induced Damage of Potassium Dihydrogen Phosphate (KDP) Optical Crystal Machined by Water Dissolution Ultra-Precision Polishing Method

et al. 2018

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“…KDP single crystal, which in nature is a kind of soluble inorganic salt, has both disadvantages for machining such as deliquescent, extremely soft, brittle and thermally sensitive, and advantages as excellent nonlinear electro-optic switches and frequency conversion devices such as Pockels cells and second-harmonic generation in laser-based inertial confinement fusion (ICF) research (Brereton, 2013;Lin et al, 2013;Hurricane et al, 2014). However, these distinct properties also make it extremely difficult for KDP crystals to obtain a flawless surface.…”

Section: Introductionmentioning

confidence: 99%

Water dissolution ultra-precision polishing of KDP crystal and its precision cleaning

Chen

Gao

et al. 2018

IJNM

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KDP crystal is a kind of excellent electro-optic material used in many laser facilities, which is also widely acknowledged to be extremely hard to machine. In this work, we developed a process to finish KDP crystal to a precision and clean engineering specimen. A micro-nano water dissolution principle and its planarisation mechanism in the machining process are illustrated, which turns the disadvantaged deliquescence property of KDP crystal into the driving force for ultra-precision polishing of the crystal. Micro emulsion fluid with nano water nuclei can precisely control the material removal and realise the selective polishing, thus forming a super smooth and precise surface. Then a subsequent cleaning process developed specially for this ultra-precision polishing method helps to get rid of the polishing fluid, and finally reduces the residue off the crystal to a clean and tidy surface with 1.964 nm rms roughness for engineering application.

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“…Currently, the National Ignition Facility (NIF) is devoting its efforts to the demonstration of fusion laser ignition [1]. Recent achievements are very promising for the development of laser fusion.…”

Section: Introductionmentioning

confidence: 99%

Transmission final lenses in the HiPER laser fusion power plant: system design for temperature control

Páramo¹,

Sordo²,

Garoz³

et al. 2014

Nucl. Fusion

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The European laser fusion project HiPER is developing technologically feasible components for a laser fusion power plant with an evacuated dry wall chamber which is likely to operate with a shock ignition scheme and direct targets. One of the key components is the final optics. In this work, we consider silica transmission final lenses and address the major issues regarding the unavoidable neutron irradiation they must withstand. For pre-commercial power plants (150 MJ target yield at 10 Hz) a distance of 16 m between the final lenses and target leads to maximum lens temperatures within tolerable limits. However, a non-uniform steady-state temperature profile is a major concern because it is the origin of unacceptable aberrations that severely affect the target spots. We have devised an active intervention system based on a heat-transfer fluid to keep the temperature profile as smooth as possible. The main characteristics of the temperature control system are defined throughout this work and enable the operation of the plant, both for the start-up procedure and for normal operation.

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Overview of the National Ignition Facility

Cited by 3 publications

References 4 publications

Laser Induced Damage of Potassium Dihydrogen Phosphate (KDP) Optical Crystal Machined by Water Dissolution Ultra-Precision Polishing Method

Laser Induced Damage of Potassium Dihydrogen Phosphate (KDP) Optical Crystal Machined by Water Dissolution Ultra-Precision Polishing Method

Water dissolution ultra-precision polishing of KDP crystal and its precision cleaning

Transmission final lenses in the HiPER laser fusion power plant: system design for temperature control

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