Visualizing deceleration-phase instabilities in inertial confinement fusion implosions using an “enhanced self-emission” technique at the National Ignition Facility

Pickworth, L.; Hammel, B. A.; Smalyuk, V. A.; Robey, H. F.; Benedetti, L. R.; Hopkins, L. Berzak; Bradley, D. K.; Field, J. E.; Haan, S. W.; Hatarik, R.; Hartouni, E. P.; Izumi, N.; Johnson, S.; Khan, S. F.; Lahmann, B.; Landen, O. L.; Pape, S. Le; MacPhee, A. G.; Meezan, N. B.; Milovich, J. L.; Nagel, S. R.; Nikroo, A.; Pak, A.; Petrasso, R. D.; Remington, B. A.; Rice, N.; Springer, P. T.; Stadermann, Michael; Widmann, K.; Hsing, W. W.

doi:10.1063/1.5025188

Cited by 24 publications

(9 citation statements)

References 86 publications

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“…The origin of these perturbations (shown as 'meteors' in figure 14(b)) is currently not well understood and a subject of investigations by the indirect-drive program. In related experiments, the mode 1 asymmetry of the x-ray emission was correlated with the motion of the hot spot during peak compression [42]. These experiments also allowed studies of radiation-cooling effects on the neutron yield.…”

Section: 'Self-emission' Platform In the Deceleration Phasementioning

confidence: 94%

“…In another experiment (see figure 14(b)), a large number of the high-mode perturbations were detected in the implosion [43]. The origin of these perturbations (shown as 'meteors' in figure 14(b)) is currently not well understood and a subject of investigations by the indirect-drive program.…”

Section: 'Self-emission' Platform In the Deceleration Phasementioning

confidence: 99%

“…One of the techniques to study perturbations and asymmetries in the deceleration phase of implosions has been the 'selfemission' platform [42]. Figure 13 shows capsule schematics with a nominal baseline configuration (figure 13(a)) and with an 'imaging' high-Z doped layer extended to the inner shell surface.…”

Section: 'Self-emission' Platform In the Deceleration Phasementioning

confidence: 99%

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Review of hydrodynamic instability experiments in inertially confined fusion implosions on National Ignition Facility

Smalyuk

Weber

Landen

et al. 2019

Plasma Phys. Control. Fusion

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Hydrodynamic instabilities are a major factor in degradation of inertial confinement fusion (ICF) implosions. In the highest performing implosions on National Ignition Facility, yield amplification (YA) due to alpha particle heating approached ∼3, while YA of ∼15-30 is needed for ignition. Understanding and mitigation of the instabilities are critical to achieving ignition. This article reviews several experimental platforms that have been developed to directly measure these instabilities in all phases of ICF implosions. Measurements of ripple-shock propagation at OMEGA laser has provided results on initial seeds for the instabilities in three ablators-plastic (CH), beryllium, and high-density carbon. At the ablation front, instability growth of preimposed modulations was measured in the linear regime using the hydrodynamic growth radiography platform. This platform was extended for modulation growth of 'native roughness' modulations and engineering features (fill tubes and capsule support membranes or 'tents'). Several new experimental platforms have or are being developed to measure instability growth at the ablator-ice interface. In the deceleration phase of implosions, complementary 'self-emission' and 'self-backlighting' platforms were developed to measure low-mode asymmetries and highmode perturbations near peak compression.

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Section: 'Self-emission' Platform In the Deceleration Phasementioning

confidence: 94%

Section: 'Self-emission' Platform In the Deceleration Phasementioning

confidence: 99%

Section: 'Self-emission' Platform In the Deceleration Phasementioning

confidence: 99%

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Review of hydrodynamic instability experiments in inertially confined fusion implosions on National Ignition Facility

Smalyuk

Weber

Landen

et al. 2019

Plasma Phys. Control. Fusion

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“…High resolution velocimetry measurements of the expansion of the rear surface of ablator materials has shown that perturbations may be seeded by the microstructure in crystalline materials such as beryllium and diamond [89] and is sensitive to both the crystalline structure and shock pressure. Efforts are underway to develop techniques that can measure mix at high convergence ratios (~10-20) related to the ablator/ice interfaces using x-ray self-emission backlighting [90,91], high resolution imaging with a spherical crystal imager [92], and cylindrical implosion platforms [93].…”

Section: High Mode Asymmetriesmentioning

confidence: 99%

Progress of indirect drive inertial confinement fusion in the United States

Kline¹,

Batha²,

Benedetti³

et al. 2019

Nucl. Fusion

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Indirect drive converts high power laser light into x-rays using small high-Z cavities called hohlraums. X-rays generated at the hohlraum walls drive a capsule filled with deuterium–tritium (DT) fuel to fusion conditions. Recent experiments have produced fusion yields exceeding 50 kJ where alpha heating provides ~3× increase in yield over PdV work. Closing the gaps toward ignition is challenging, requiring optimization of the target/implosions and the laser to extract maximum energy. The US program has a three-pronged approach to maximize target performance, each closing some portion of the gap. The first item is optimizing the hohlraum to couple more energy to the capsule while maintaining symmetry control. Novel hohlraum designs are being pursued that enable a larger capsule to be driven symmetrically to both reduce 3D effects and increase energy coupled to the capsule. The second issue being addressed is capsule stability. Seeding of instabilities by the hardware used to mount the capsule and fill it with DT fuel remains a concern. Work reducing the impact of the DT fill tubes and novel capsule mounts is being pursed to reduce the effect of mix on the capsule implosions. There is also growing evidence native capsule seeds such as a micro-structure may be playing a role on limiting capsule performance and dedicated experiments are being developed to better understand the phenomenon. The last area of emphasis is the laser. As technology progresses and understanding of laser damage/mitigation advances, increasing the laser energy seems possible. This would increase the amount of energy available to couple to the capsule, and allow larger capsules, potentially increasing the hot spot pressure and confinement time. The combination of each of these focus areas has the potential to produce conditions to initiate thermo-nuclear ignition.

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“…So the high spatial resolution imaging diagnostics in a high X-ray energy band are necessary. Recently, the hydrodynamic instability growth radiography in the ICF [7,8] and some other high energy density physics (HEDP) experiments also employ more and more high resolution imaging diagnostics. The Kirkpatrick-Baez (KB) microscope is an advanced X-ray imaging system, with a high spatial resolution (several µm) and a high light collection efficiency (∼ 10 −7 ).…”

Section: Introductionmentioning

confidence: 99%

A four-channels reflective Kirkpatrick-Baez microscope for the hot spot diagnostic in the 100 kJ laser driven inertial confinement fusion in China

Zhang

Chen

et al. 2019

J. Inst.

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A high quality hot spot is crucial in the laser driven inertial confinement fusion. The hot spot self-emitted X-ray images in a high spatial resolution may be used to analyze the hot spot asymmetry and some fine structures induced by mix. The high spatial resolved X-ray imaging diagnostics can also serve in the hydrodynamic instability growth radiography and some other physical research in the inertial confinement fusion. The Kirkpatrick-Baez microscope can provide a higher resolution and throughput efficiency diagnostic. A new four-channels KB microscope was designed and built for the < 10 keV X-ray imaging. The Pt coated reflective mirror pairs were used to obtain a wide grazing angle bandwidth. The variation of the X-ray reflectivity was small in a large field of view. The microscope had a magnification of about 20. The spatial resolution in the central field of view was about 7 µm. The similarities between the different channel images were about 97%. The KB microscope is in operation in the directly or indirectly driven implosions by 10-100 kJ lasers on Shenguang laser facility in China. The time-integral hot spot asymmetry has been diagnosed, and the time-resolved imaging will be implemented in the following work. K: Plasma diagnostics -interferometry, spectroscopy and imaging; Plasma diagnosticshigh speed photography 1Corresponding author.

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Visualizing deceleration-phase instabilities in inertial confinement fusion implosions using an “enhanced self-emission” technique at the National Ignition Facility

Cited by 24 publications

References 86 publications

Review of hydrodynamic instability experiments in inertially confined fusion implosions on National Ignition Facility

Review of hydrodynamic instability experiments in inertially confined fusion implosions on National Ignition Facility

Progress of indirect drive inertial confinement fusion in the United States

A four-channels reflective Kirkpatrick-Baez microscope for the hot spot diagnostic in the 100 kJ laser driven inertial confinement fusion in China

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