Diagnosing and mitigating laser preheat induced mix in MagLIF
- Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
- General Atomics, San Diego, CA (United States)
A series of Magnetized Liner Inertial Fusion (MagLIF) experiments have been conducted in order to investigate the mix introduced from various target surfaces during the laser preheat stage. The material mixing was measured spectroscopically for a variety of preheat protocols by employing mid-atomic number surface coatings applied to different regions of the MagLIF target. The data show that the material from the top cushion region of the target can be mixed into the fuel during preheat. For some preheat protocols, our experiments show that the laser-entrance-hole (LEH) foil used to contain the fuel can be transported into the fuel a significant fraction of the stagnation length and degrade the target performance. Preheat protocols using pulse shapes of a few-ns duration result in the observable LEH foil mix both with and without phase-plate beam smoothing. In order to reduce this material mixing, a new capability was developed to allow for a low energy (~20 J) laser pre-pulse to be delivered early in time (–20 ns) before the main laser pulse (~1.5 kJ). In experiments, this preheat protocol showed no indications of the LEH foil mix. As a result, the experimental results are broadly in agreement with pre-shot two-dimensional HYDRA simulations that helped motivate the development of the early pre-pulse capability.
- Research Organization:
- Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
- Sponsoring Organization:
- USDOE National Nuclear Security Administration (NNSA)
- Grant/Contract Number:
- AC04-94AL85000
- OSTI ID:
- 1492367
- Report Number(s):
- SAND-2018-13636J; 670631
- Journal Information:
- Physics of Plasmas, Vol. 25, Issue 11; ISSN 1070-664X
- Publisher:
- American Institute of Physics (AIP)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
Web of Science
Constraining preheat energy deposition in MagLIF experiments with multi-frame shadowgraphy
|
journal | March 2019 |
Nernst thermomagnetic waves in magnetized high energy density plasmas
|
journal | November 2019 |
Similar Records
The effect of laser entrance hole foil thickness on MagLIF-relevant laser preheat
Scaling laser preheat for MagLIF with the Z-Beamlet laser