Expand this Topic clickable element to expand a topic
Skip to content
Optica Publishing Group
Journal Home About Issues in Progress Current Issue All Issues Early Posting Feature Issues

Hohlraum fields with monoenergetic proton radiography at OMEGA

Jacob A. Pearcy, Graeme D. Sutcliffe, Timothy M. Johnson, Benjamin L. Reichelt, Skylar G. Dannhoff, Yousef Lawrence, Johan Frenje, Maria Gatu-Johnson, Rich D. Petrasso, and Chikang Li

Open Access Open Access

Abstract

A more complete understanding of laser-driven hohlraum plasmas is critical for the continued development and improvement of ICF experiments. In these hohlraums, self-generated electric and magnetic fields can play an important role in modifying plasma properties such as heat transport; however, the strength and distribution of electromagnetic fields in such hohlraums remain largely uncertain. To explore this question, we conducted experiments at the OMEGA laser facility, using monoenergetic proton radiography to probe laser-driven vacuum hohlraums. We then utilized reconstructive methods to recover information about proton deflections. To interpret these reconstructions, a new technique for detangling the contributions of electric and magnetic fields to proton deflections was developed. This work was supported in part by the U.S. Department of Energy, the National Laser Users’ Facility, and the Laboratory for Laser Energetics.

© 2024 Optica Publishing Group

Full Article  |  PDF Article
More Like This
Design of proton deflectometry with in situ x-ray fiducial for magnetized high-energy-density systems

Sophia Malko, Courtney Johnson, Derek B. Schaeffer, William Fox, and Gennady Fiksel
Appl. Opt. 61(6) C133-C142 (2022)

Picosecond laser-driven coded-source radiography with high resolution and contrast

Mengting Li, Tiankui Zhang, Shaoyi Wang, Minghai Yu, Fang Tan, Yonghong Yan, Yue Yang, Jiaxing Wen, Yuchi Wu, Jingqin Su, Weimin Zhou, and Yuqiu Gu
Opt. Express 32(10) 16809-16822 (2024)

Ultra-intense femtosecond laser interactions with aligned nanostructures

Jorge J. Rocca, Maria G. Capeluto, Reed C. Hollinger, Shoujun Wang, Yong Wang, G. Ravindra Kumar, Amit D. Lad, Alexander Pukhov, and Vyacheslav N. Shlyaptsev
Optica 11(3) 437-453 (2024)

View More...

Data availability

Data underlying the results presented in this paper are not publicly available at this time but may be obtained from the authors upon reasonable request.

Cited By

Optica participates in Crossref's Cited-By Linking service. Citing articles from Optica Publishing Group journals and other participating publishers are listed here.

Alert me when this article is cited.


Figures (9)
Fig. 1.
Fig. 1. Cartoon of the experimental setup, showing the capsule backlighter suspended by a stalk at left, and the hohlraum suspended by a stalk on the right. Dotted arrows schematically represent proton trajectories from the backlighter, while the red shaded areas denote the 9 drive laser beams on the hohlraum. For clarity, the 40 drive beams aimed at the backlighter are not pictured.

Download Full Size | PDF

Fig. 2.
Fig. 2. The processed proton radiography images of the vacuum hohlraum; the image on the left was formed by 14.7 MeV ${{\rm D}^3}{\rm He}$ protons, while the image on the right was formed by 3 MeV DD protons. In these images, the 14.7 MeV protons sampled the hohlraum fields ${\sim}1.4\;{\rm ns} $ after the start of the hohlraum drive. The ninefold symmetry of these radiographs reflects the 9-beam axisymmetric laser drive on the hohlraum, while the dark central feature indicates a focusing of protons towards the center of the image. These images will be used to demonstrate the novel methods for electromagnetic field discrimination from deflection field reconstruction.

Download Full Size | PDF

Fig. 3.
Fig. 3. A cartoon showing the approximate geometry of the experiment (dimensions of objects and lengths are not drawn to scale). The $\hat z$ direction points horizontally to the right of the image. At the far left is a cyan sphere representing the capsule-type proton source; from it, dotted lines representing proton trajectories emanate. The protons traverse a distance $\ell$ before encountering the orange subject plasma, which has perpendicular extent ${l_{\bot ,p}}$; their positions before being disturbed by the plasma conditions are ${\vec x_{\bot ,0}} = ({x_{\bot ,0}},{y_{\bot ,0}})$. They interact with the subject plasma over a distance ${l_p}$ before continuing to propagate to the screen over a distance of $L$; their coordinates at the screen are $\vec x_ \bot ^{(s)} = ({x_ \bot ^{(s)},y_ \bot ^{(s)}})$.

Download Full Size | PDF

Fig. 4.
Fig. 4. A heat map showing the magnitude of the perpendicular deflection $|\vec w|$ field as inferred from the 14.7 MeV proton image. The two red rings denote the boundary between regions ${R_i}$ selected for different field fractions and the outer boundary of the reconstruction region, respectively.

Download Full Size | PDF

Fig. 5.
Fig. 5. Color maps of the field fraction breakdowns assigned to each image; the color bar is common to each map. In the figure titles, ${f_1}$ is the field fraction in the inner region ${R_1}$, while ${f_2}$ is the field fraction in the outer region ${R_2}$. Information outside the reconstruction region is ignored.

Download Full Size | PDF

Fig. 6.
Fig. 6. Synthetic DD proton images produced from the deflection fields calculated from the electromagnetic field configurations implied by the field fraction breakdowns in Fig. 5. Both the inner and outer regions show clear variations in feature sizes and locations with field fraction, which can be used as comparisons with the true DD proton data in Fig. 2. These images have had a Gaussian blur applied in post-processing to simulate plasma scattering conditions present in the actual DD proton data. The color bar denotes proton flux relative to the mean flux in each image.

Download Full Size | PDF

Fig. 7.
Fig. 7. A) Matrix of field fraction breakdowns showing colors that quantify the residual values between a radial profile of the conjectured reconstruction and a radial profile of the actual DD data. The units on the color axis are arbitrary. The fit with lowest residual is clearly visible as the dark blue square. B) Direct comparison of radial lineouts between the best fit and the DD proton data. Note that in the conjectured reconstruction, pixel values outside the outer radius of reconstruction are artificially zeroed.

Download Full Size | PDF

Fig. 8.
Fig. 8. Direct side-by-side visual comparison of the calculated best-fit synthetic DD proton image (on the left) and the DD proton data (on the right). Although not a perfect reproduction, gross features common to both are clearly identifiable, suggesting that the fit is reasonable.

Download Full Size | PDF

Fig. 9.
Fig. 9. Inferred path-integrated electric and magnetic fields taken from the best-fit field fraction breakdown. All quantities quoted are integrated along the $\hat z$-direction of proton propagation.

Download Full Size | PDF

Equations (3)

Equations on this page are rendered with MathJax. Learn more.

Ψ ( x → ⊥ ( s ) ) = Ψ 0 det ( ∇ 0 ( x → ⊥ ( s ) ) ) ,
x → ⊥ ( s ) ( x → ⊥ , 0 ) = L + ℓ ℓ x → ⊥ , 0 + L v w → ( x → ⊥ , 0 ) ,
w → = q m c ∫ ℓ ( z ^ × B → ) d z + q 2 m W ∫ ℓ E → d z ≡ w → B + w → E .
Select as filters
Select Topics Cancel
Top
       
© Copyright 2024 | Optica Publishing Group. All rights reserved, including rights for text and data mining and training of artificial technologies or similar technologies.
Privacy | Terms of Use