New HANE Fireball Physics: Implications for US Infrastructure Vulnerability
The vulnerability of the US infrastructure to High altitude Nuclear Explosions (HANEs) continues to be the object of studies by a number of blue-ribbon panels and commissions. In particular, studies suggest an alarming sensitivity of our electronic infrastructure to some types of ElectroMagnetic Pulse (EMP) while other types of EMP threaten our power distribution systems. Equally or perhaps more important is the concern that a large percentage of our satellites will experience 'upsets' or worse from these same HANE effects. Such studies, however, are all based on the sparse data obtained during the last HANE tests conducted in the early 1960's. A weakness in our present understanding is that almost all the conclusions about distributed-electric-current-driven EMP, with time scales 1/2 second or longer, are interpretations of old data guided by the computational MHD/fluid models available at the time. Fluid models make the assumption that the mean-free-path is zero and thus miss important physics regardless of the model used to couple ion motion to the magnetic field. Even when planetary length scales are modeled so that the gyro radius becomes negligible, the early dynamics of the fireball are not properly captured. The facts are, at relevant altitudes, the explosion expansion is almost unimpeded by the tenuous ionospheric background-particle mean-free-paths are of order 10,000 km. The primary impediment to the debris expansion is the earth's magnetic field bending the energetic ion trajectories emanating from the explosion into circular orbits with typical radii that range from 200 km for heavy ions to 10 km or less for the lighter ions in the debris. These particles thus gyrate many times before they are stopped by a collision with the background atmosphere. Only models that track ion gyro-motion can recover the myriad possibilities through which the complicated, energetic, 'fireball' of debris may evolve. Fireball evolution is important because it determines debris distribution (crucial in satellite vulnerability studies) and generation of low frequency EMP. With the previous considerations as motivation, we have recently reconsidered the early fireball dynamics to see if more appropriate physics models would reveal new insight into some long-standing problems, such as the apparent need for 'jetting' of debris particles to high altitude to explain the observed satellite damage. Additionally, we hoped that the additional physics might reveal new aspects of the early fireball dynamics that could augment the rather incomplete understanding we now have of the EMP generated by such tests.
- Research Organization:
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 951167
- Report Number(s):
- LLNL-CONF-410189; TRN: US200911%%361
- Resource Relation:
- Conference: Presented at: Hardened Electronics and Radiation Technology HEART 2009, Albuquerque, NM, United States, Mar 30 - Apr 03, 2009
- Country of Publication:
- United States
- Language:
- English
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