The Daedalus sensor is the next version of the nanosecond time-gated, multi-frame hybridized CMOS (hCMOS) x-ray sensor, developed by Sandia National Laboratories (SNL). The Daedalus sensor leverages previous hCMOS features such as nanosecond gated frames while expanding features for increased record length, improved full well depth, and one-side abutment capability. The second version of the Daedalus sensor, the DV2, resolves an increased record length feature called interlacing in addition to the sensor’s ability to hold the integrated electrical charge from photocurrent for longer periods of time needed for full dynamic range during readout. The DV2 sensor characteristics, including background oscillations, skew, key sensor features for timing and high full well, and mapping of the internal temperature sensor are presented and discussed.
B. Bachmann, H. Abu-Shawareb, N. Alexander, J. Ayers, C. Bailey, P. Bell, L. Benedetti, D. Bradley, G. Collins, L. Divol, T. Döppner, S. Felker, J. Field, A. Forsman, J. Galbraith, C. Hardy, T. Hilsabeck, N. Izumi, C. Jarrot, J. Kilkenny, S. Kramer, O. Landen, T. Ma, A. MacPhee, N. Masters, S. Nagel, A. Pak, P. Patel, L. Pickworth, J. Ralph, C. Reed, J. Rygg, D. Thorn
X-ray penumbral imaging has been successfully fielded on a variety of inertial confinement fusion (ICF) capsule
implosion experiments on the National Ignition Facility (NIF). We have demonstrated sub-5 μm resolution imaging of
stagnated plasma cores (hot spots) at x-ray energies from 6 to 30 keV. These measurements are crucial for improving
our understanding of the hot deuterium-tritium fuel assembly, which can be affected by various mechanisms, including
complex 3-D perturbations caused by the support tent, fill tube or capsule surface roughness. Here we present the
progress on several approaches to improve x-ray penumbral imaging experiments on the NIF. We will discuss
experimental setups that include penumbral imaging from multiple lines-of-sight, target mounted penumbral apertures
and variably filtered penumbral images. Such setups will improve the signal-to-noise ratio and the spatial imaging
resolution, with the goal of enabling spatially resolved measurements of the hot spot electron temperature and material
mix in ICF implosions.
We present new designs for the launch and receiver boards used in a high speed x-ray framing camera at the National Ignition Facility. The new launch board uses a Klopfenstein taper to match the 50 ohm input impedance to the ~10 ohm microchannel plate. The new receiver board incorporates design changes resulting in an output monitor pulse shape that more accurately represents the pulse shape at the input and across the microchannel plate; this is valuable for assessing and monitoring the electrical performance of the assembled framing camera head. The launch and receiver boards maximize power coupling to the microchannel plate, minimize cross talk between channels, and minimize reflections. We discuss some of the design tradeoffs we explored, and present modeling results and measured performance. We also present our methods for dealing with the non-ideal behavior of coupling capacitors and terminating resistors. We compare the performance of these new designs to that of some earlier designs.
As neutron yields increase at the National Ignition Facility (NIF) the need for neutron ‘hardened’ diagnostics has also
increased. Gated Imagers located within the target chamber are exposed to neutrons which degrade image quality and
damage electronics. In an effort to maintain the signal to noise ratio (S/N) on our images and mitigate neutron induced
damage, we have implemented numerous upgrades to our X-ray framing cameras. The NIF Gated X-ray Detector
(GXD), design has evolved into the Hardened Gated X-ray Detector, HGXD. These improvements are presented with
image data taken on high yield NIF shots showing enhanced image quality. Additional upgrades were added to remotely
locate sensitive electronics and ease operational use.
V. Smalyuk, J. Ayers, P. Bell, L. R. Benedetti, D. Bradley, C. Cerjan, J. Emig, B. Felker, S. Glenn, C. Hagmann, J. Holder, N. Izumi, J. Kilkenny, J. Koch, O. Landen, J. Moody, K. Piston, N. Simanovskaia, C. Walton
X-ray imaging diagnostics instruments will operate in a harsh ionizing radiation background environment during ignition
experiments at the National Ignition Facility (NIF). This background consists of mostly neutrons and gamma rays
produced by inelastic scattering of neutrons. An imaging system, M-ARIANE (Mirror-assisted Active Readout In A
Neutron Environment), based on an x-ray framing camera with film, has been designed to operate in such a harsh
neutron-induced background environment. Multilayer x-ray mirrors and a shielding enclosure are the key components of
this imaging system which is designed to operate at ignition neutron yields of ~1e18 on NIF. Modeling of the neutronand
gamma-induced backgrounds along with the signal and noise of the x-ray imaging system is presented that display
the effectiveness of this design.
We present evidence of an artifact in gated x-ray framing cameras that can severely impact image quality. This artifact
presents as a spatially-varying, high-intensity background and is correlated with experiments that produce a high flux of
x-rays during the time before the framing camera is triggered. Dedicated experiments using a short pulse UV laser that
arrives before, during, and after the triggering of the framing camera confirm that these artifacts can be produced by light
that arrives in advance of the voltage pulse that triggers the camera. This is consistent with these artifacts being the
result of photoelectrons produced uniformly at the active area of the camera by early incident light and then selectively
trapped by the electromagnetic (EM) fields of the camera. Simulations confirm that the EM field above the active
surface can act to confine electrons produced before the camera is triggered. We further present a method to suppress
these artifacts by installing a conducting electrode in front of the active area of the framing camera. This device
suppresses artifacts by attracting any electrons liberated by x-rays that arrive before the camera is triggered.
X-ray imaging is integral to the measurement of the properties of hot plasmas. To this end, a suite of gated x-ray imagers
have been developed for use in a wide range of experiments at the National Ignition Facility (NIF). These instruments
are sensitive to x-rays over the range of 0.7-90keV and can acquire images at 20ps intervals for source intensities
ranging over several orders of magnitude. We review the design, technology, and construction of these instruments and
present recent results obtained from NIF experiments in which gated x-ray imagers have played a key role.
The radiation environment associated with Inertial Confinement Fusion (ICF) experiments presents unique challenges
for x-ray imaging. We report on the performance of gated imagers that have been optimized for this harsh environment
and describe diagnostics to be deployed in the near future that will provide x-ray images of imploding ICF capsules in
the presence of backgrounds associated with neutron yields above 1016. Such images will provide crucial data that will
enable even higher neutron yields and successful ignition.
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