to operate at longer implosion times. This would obviously be a huge lever arm on the total system that requires further investigation.

• The MagLIF performance scaling simulations have been primarily performed in 1-D, with limited exploration of 2-D Rayleigh-Taylor instability issues. However, the physics of thermal conduction and transport in magnetized plasmas is fully 3-D in nature and requires exploration in greater detail. 1-D simulations provide ideal energy scaling; 2-D begins to bring in Rayleigh-Taylor instabilities. Magnetized performance, however, will require 3-D studies.

• As stated by Sandia, “batch burn” (volume ignition) will result in a low yield, and a “levitated fuel” layer should give better performance. This will require additional calculations, target fabrication techniques, and experimental implementation. While providing improved performance, it also makes the fabrication and fielding logistics in a fusion power plant more complicated.

• Traditional magnetized target fusion concepts have not been shown to scale to high yield and gain. Sandia states that it has recently calculated high-yield performance with MagLIF targets. However, the additional cost of the magnets and optics that would be destroyed on each shot and the complexity of transporting the heater laser through the thick-liquid-wall chamber environment must both be accounted for in the system economics and design.

• References from the 2005 Sandia IFE program discuss potential issues of operating RTLs if the final radius and gap become too small. At that time the baseline power flow was relatively large wire-array Z-pinches. It will be important to study the compatibility of the RTL concept with the smaller diameter of direct magnetic-drive targets.

Potential for Use in an IFE System

Concepts for IFE systems using Z-pinch targets were presented to the panel,19 but sufficient uncertainties remain that it would be premature to attempt an evaluation at this time. As presently envisioned, each 3-GJ fusion energy pulse would require the insertion, connection, and energizing of an RTL and fusion target assembly at a 0.1 Hz repetition rate. The assembly comprises an evacuated RTL system that contains the cryogenically cooled Z-pinch target at its center. The details of this concept are complex and will require extensive research and development if Z-pinches are pursued as an IFE technology. It is too early in both the target physics and fusion technology research programs to evaluate the target

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19 M. Cuneo et al., Sandia National Laboratories, “The Potential for a Z-pinch Fusion System for IFE,” presentation to the panel on May 10, 2011.



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