Fast resistive bolometry

Spielman, R. B.; Deeney, C.; Fehl, D. L.; Hanson, D. L.; Keltner, N.R.; McGurn, J.; McKenney, J. L.

doi:10.1063/1.1149488

Cited by 71 publications

(28 citation statements)

References 5 publications

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“…The accuracy of resistive bolometer measurements [67] is particularly important, because pinch power waveforms are obtained at present by normalizing XRD waveforms (and, in the future, TEP waveforms) to absolute bolometer energy measurements. Bolometers are high fluence, time-resolved fast-pulse x-ray diagnostics with flat spectral response whose calibration is derived from the intrinsic material properties and geometry of the resistance elements.…”

Section: V2 Calibration Of Z-pinch X-ray Energy and Power Diagnosticsmentioning

confidence: 99%

“…9), with one LOS pipe section extending to 26 m. The LOS 5/6 diagnostics package is designed to provide the primary x-ray energy, power, and spectral measurements of the z-pinch itself. Five port locations exist and are typically used to field instruments including a bolometer array [67], an x-ray diode (XRD) array [68], a photoconducting detector (PCD) array [69][70][71], a transmission grating spectrometer (TGS) [43] (Fig. 10), and a total energy and power (TEP) diagnostic [72] or a calorimeter [73].…”

Section: Iii2 Upgrade Of the Los 5/6 Diagnostics Packagementioning

confidence: 99%

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Diagnostics development plan for ZR.

Hanson¹

2003

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The Z Refurbishment (ZR) Project is a program to upgrade the Z machine at SNL with modern durable pulsed power technology, providing additional shot capacity and improved reliability as well as advanced capabilities for both pulsed x-ray production and high pressure generation. The development of enhanced diagnostic capabilities is an essential requirement for ZR to meet critical mission needs. This report presents a comprehensive plan for diagnostic instrument and infrastructure development for the first few years of ZR operation. The focus of the plan is on: (1) developing diagnostic instruments with high spatial and temporal resolution, capable of low noise operation and survival in the severe EMP, bremsstrahlung, and blast environments of ZR; and (2) providing diagnostic infrastructure improvements, including reduced diagnostic trigger signal jitter, more and flexible diagnostic line-of-sight access, and the capability for efficient exchange of diagnostics with other laboratories. This diagnostic plan is the first step in an extended process to provide enhanced diagnostic capabilities for ZR to meet the diverse programmatic needs of a broad range of defense, energy, and general science programs of an international user community into the next decade. ZR Diagnostics Development Plan ________________________________________________________________________ 4 AcknowledgementsThe author would like to thank

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Section: V2 Calibration Of Z-pinch X-ray Energy and Power Diagnosticsmentioning

confidence: 99%

Section: Iii2 Upgrade Of the Los 5/6 Diagnostics Packagementioning

confidence: 99%

Diagnostics development plan for ZR.

Hanson¹

2003

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“…The issue of energy coupling will be discussed further in the context of post-shot simulations of experimental data presented below. LOS A and LOS B each fielded a 5 µm kimfol filtered x-ray detector (XRD) [29] (a) (b) (c) and a bare Ni bolometer [30] to characterize the total radiated soft x-ray power and yield. The bolometer provides a measurement of total yield expected to be accurate to 15%.…”

Section: Return Current Cagementioning

confidence: 99%

Planar wire array performance scaling at multi-MA levels on the Saturn generator.

Chuvatin

Jones²,

Vesey³

et al. 2007

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A series of twelve shots were performed on the Saturn generator in order to conduct an initial evaluation of the planar wire array z-pinch concept at multi-MA current levels. Planar wire arrays, in which all wires lie in a single plane, could offer advantages over standard cylindrical wire arrays for driving hohlraums for inertial confinement fusion studies as the surface area of the electrodes in the load region (which serve as hohlraum walls) may be substantially reduced. In these experiments, mass and array width scans were performed using tungsten wires. A maximum total radiated x-ray power of 10±2 TW was observed with 20 mm wide arrays imploding in ∼100 ns at a load current of ∼3 MA, limited by the high inductance. Decreased power in the 4-6 TW range was observed at the smallest width studied (8 mm). 10 kJ of Al K-shell x-rays were obtained in one Al planar array fielded. This report will discuss the zero-dimensional calculations used to design the loads, the results of the experiments, and potential future research to determine if planar wire arrays will continue to scale favorably at current levels typical of the Z machine. Implosion dynamics will be discussed, including x-ray self-emission imaging used to infer the velocity of the implosion front and the potential role of trailing mass. Resistive heating has been previously cited as the cause for enhanced yields observed in excess of jxB-coupled energy. The analysis presented in this report suggests that jxBcoupled energy may explain as much as the energy in the first x-ray pulse but not the total yield, which is similar to our present understanding of cylindrical wire array behavior.4 Acknowledgment

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“…In [23] were fielded in 2008, and the measured total x-ray yields (differing by 10-15%) were averaged. A 5 μm kimfol filtered x-ray detector (XRD) [24] was normalized to the average yield in order to quote peak x-ray power.…”

Section: Description Of X-ray Diagnosticsmentioning

confidence: 99%

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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Fast resistive bolometry

Cited by 71 publications

References 5 publications

Diagnostics development plan for ZR.

Diagnostics development plan for ZR.

Planar wire array performance scaling at multi-MA levels on the Saturn generator.

Compact wire array sources: power scaling and implosion physics.

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