Assessing the ZR Machine's Potential for Producing Multi-keV X-Ray Yields in K-Shell Line and Free-Bound Continuum Radiation

Thornhill, J. W.; Velikovich, A. L.; Clark, Robert W.; Apruzese, J. P.; Davis, J.; Whitney, K. G.; Coleman, P.L.; Coverdale, C. A.; Deeney, C.; LePell, P.D.

doi:10.1109/tps.2006.883380

Cited by 40 publications

(21 citation statements)

References 25 publications

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“…[48] does a reasonable job of approximating the measured K-shell yield from cylindrical Al wire arrays on Saturn (compare Tables 3.5 and 3.6). This load is seen to be low enough mass that the impact of radiative cooling is unimportant (f = 0.3, its maximum allowed value), and the load is right at the transition point between inefficient and efficient radiation regimes (S = 0.91).…”

Section: Aluminum K-shell Radiation From a Planar Wire Arraymentioning

confidence: 90%

“…where E i = Am p E jxB /ml is the energy coupled per ion of atomic mass A in a z pinch of mass per unit length m and length l, E jxB is the total energy coupled by the generator to the load, m p is the proton mass, and E min ≈ 1.012Z 3.662 eV/ion is the minimum energy to ionize to the K-shell [46,47,48]. A general guideline is that η > 2 is desired in order to generate appreciable K-shell radiation from a z pinch plasma of any atomic number Z.…”

Section: Aluminum K-shell Radiation From a Planar Wire Arraymentioning

confidence: 99%

“…K-shell scaling model of Ref. [48] applied to the Al wire array shots of Table 3.5. Cases of 50% and 100% participation of the initial mass m 0 in the implosion are considered for the planar wire arrays.…”

Section: Aluminum K-shell Radiation From a Planar Wire Arraymentioning

confidence: 99%

“…[48]. In this work, a phenomenological model for K-shell yield is formulated and benchmarked to single cylindrical wire array data from the Z machine.…”

Section: Aluminum K-shell Radiation From a Planar Wire Arraymentioning

confidence: 99%

“…The scaling coefficient is taken as c (Z = 13, load) = 47, scaled as Z 2.9 from the value benchmarked to Ar implosions per Ref. [48]. This coefficient can depend on the configuration of the load, and we might expect it to be different for planar arrays compared to cylindrical arrays due to the differences in implosion dynamics discussed earlier.…”

Section: Aluminum K-shell Radiation From a Planar Wire Arraymentioning

confidence: 99%

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Compact wire array sources: power scaling and implosion physics.

Serrano¹,

Chuvatin

Jones³

et al. 2008

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A series of ten shots were performed on the Saturn generator in short pulse mode in order to study planar and small-diameter cylindrical tungsten wire arrays at ∼5 MA current levels and 50-60 ns implosion times as candidates for compact z-pinch radiation sources. A new vacuum hohlraum configuration has been proposed in which multiple z pinches are driven in parallel by a pulsed power generator. Each pinch resides in a separate return current cage, serving also as a primary hohlraum. A collection of such radiation sources surround a compact secondary hohlraum, which may potentially provide an attractive Planckian radiation source or house an inertial confinement fusion fuel capsule. Prior to studying this concept experimentally or numerically, advanced compact wire array loads must be developed and their scaling behavior understood. The 2008 Saturn planar array experiments extend the data set presented in Ref.[1], which studied planar arrays at ∼3 MA, 100 ns in Saturn long pulse mode. Planar wire array power and yield scaling studies now include current levels directly applicable to multi-pinch experiments that could be performed on the 25 MA Z machine. A maximum total x-ray power of 15 TW (250 kJ in the main pulse, 330 kJ total yield) was observed with a 12-mm-wide planar array at 5.3 MA, 52 ns. The full data set indicates power scaling that is sub-quadratic with load current, while total and main pulse yields are closer to quadratic; these trends are similar to observations of compact cylindrical tungsten arrays on Z. We continue the investigation of energy coupling in these short pulse Saturn experiments using zero-dimensional-type implosion modeling and pinhole imaging, indicating 16 cm/μs implosion velocity in a 12-mm-wide array. The same phenomena of significant trailing mass and evidence for resistive heating are observed at 5 MA as at 3 MA. 17 kJ of Al K-shell radiation was obtained in one Al planar array fielded at 5.5 MA, 57 ns and we compare this to cylindrical array results in the context of a K-shell yield scaling model. We have also performed an initial study of compact 3 mm diameter cylindrical wire arrays, which are alternate candidates for a multi-pinch vacuum hohlraum concept. These massive 3.4 and 6 mg/cm loads may have been impacted by opacity, producing a maximum x-ray power of 7 TW at 4.5 MA, 45 ns. Future research directions in compact x-ray sources are discussed. 4 AcknowledgmentWe thank M. Lopez (1675), G. T. Liefeste (1675), and J. L. Porter (1670) for providing load hardware and diagnostic support; L.B. Nielsen-Weber (1675) and D.S. Nielsen (1675) for extensive support of diagnostic installation, fielding, and film processing;

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Section: Aluminum K-shell Radiation From a Planar Wire Arraymentioning

confidence: 90%

Section: Aluminum K-shell Radiation From a Planar Wire Arraymentioning

confidence: 99%

Section: Aluminum K-shell Radiation From a Planar Wire Arraymentioning

confidence: 99%

“…[48]. In this work, a phenomenological model for K-shell yield is formulated and benchmarked to single cylindrical wire array data from the Z machine.…”

Section: Aluminum K-shell Radiation From a Planar Wire Arraymentioning

confidence: 99%

Section: Aluminum K-shell Radiation From a Planar Wire Arraymentioning

confidence: 99%

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