Exploring the parameter space of MagLIF implosions using similarity scaling. III. Rise-time scaling

Magnetized liner inertial fusion (MagLIF) is a z-pinch magneto-inertial-fusion concept studied at the Z Pulsed Power Facility of Sandia National Laboratories. Two important metrics characterizing current delivery to a z-pinch load are the peak current and the current-rise time, which is roughly the...

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Bibliographic Details
Published in:Physics of plasmas 2023-03, Vol.30 (3)
Main Authors: Ruiz, D. E., Schmit, P. F., Weis, M. R., Peterson, K. J., Matzen, M. K.
Format: Article
Language:English
Subjects:
Electric potential
Implosions
Inertial fusion (reactor)
Linings
Load
Parameters
Performance measurement
Plasma physics
Scaling laws
Similarity
Time
Voltage
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Summary:Magnetized liner inertial fusion (MagLIF) is a z-pinch magneto-inertial-fusion concept studied at the Z Pulsed Power Facility of Sandia National Laboratories. Two important metrics characterizing current delivery to a z-pinch load are the peak current and the current-rise time, which is roughly the time interval to reach the peak current. It is known that, when driving a z-pinch load with a longer current-rise time, the performance of the z-pinch decreases. However, a theory to understand and quantify this effect is still lacking. In this paper, we utilize a framework based on similarity scaling to analytically investigate the variations in the performance of MagLIF loads when varying the current-rise time, or equivalently, the implosion timescale. To maintain similarity between the implosions, we provide scaling prescriptions of experimental input parameters defining a MagLIF load and derive the expected scaling laws for stagnation conditions and for various performance metrics. We compare predictions of the theory to 2D numerical simulations using the radiation, magneto-hydrodynamic code hydra. For several metrics, we find acceptable agreement between the theory and simulations. Our results show that the voltage φ load near the MagLIF load follows a weak scaling law φ load ∝ t φ − 0.12 with respect to the characteristic timescale t φ of the voltage source, instead of the ideal φ load ∝ t φ − 1 scaling. This occurs because the imploding height of the MagLIF load must increase to preserve end losses. As a consequence of the longer imploding liners, the required total laser preheat energy and delivered electric energy increase. Overall, this study helps understand the trade-offs of the MagLIF design space when considering future pulsed-power generators with shorter and longer current-rise times.
ISSN:1070-664X
1089-7674
DOI:10.1063/5.0126700