Microsecond ramp compression of a metallic liner driven by a 5 MA current on the SPHINX machine using a dynamic load current multiplier pulse shaping

Multiplexed Photonic Doppler Velocimetry systems are developed to measure velocities with high density in physics experiments such as shock physics on novel materials. Decreasing the mesh size can lead to crosstalk issues which can be overcome by wavelength multiplexing. Crosstalk has been characterized on a line of 8 collimators with a pitch of 1 mm. A crosstalk-free Photonic Doppler Velocimetry system with 16 telecom wavelengths was built. Wavelength multiplexing provides as well a reduction of the total number of fiber components. The system was designed for velocities up to 1000 m/s and with a bandwidth of 2 GHz. In the frequency domain, the channel spacing is 100 GHz which is more than enough to prevent any crosstalk. A ramp compression experiment was carried out by a high-pulsed-power generator to demonstrate the dynamic performances of the cross-talk free system at about 80 m/s.

Section: Ramp Compression Experimentsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Multi-wavelength crosstalk-free photonic Doppler velocimetry

Barbarin

Blanc

d’Almeida

et al. 2020

Characteristics of a molybdenum X-pinch X-ray source as a probe source for X-ray diffraction studies

Zucchini

Bland

Chauvin

et al. 2015

X-ray emission from a molybdenum X-pinch has been investigated as a potential probe for the high pressure states made in dynamic compression experiments. Studies were performed on a novel 300 kA, 400 ns generator which coupled the load directly to a low inductance capacitor and switch combination. The X-pinch load consisted of 4 crossed molybdenum wires of 13 μm diameter, crossed at an angle of 62°. The load height was 10 mm. An initial x-ray burst generated at the wire crossing point, radiated in the soft x-ray range (hυ < 10 keV). This was followed, 2-5 ns later, by at least one harder x-ray burst (hυ > 10 keV) whose power ranged from 1 to 7 MW. Time integrated spectral measurements showed that the harder bursts were dominated by K-alpha emission; though, a lower level, wide band continuum up to at least 30 keV was also present. Initial tests demonstrated that the source was capable of driving Laue diffraction experiments, probing uncompressed samples of LiF and aluminium.

Capacitive sensor for fast pulsed voltage monitor in transmission line

Wang

Ding

Qiu

2019

To monitor fast pulsed voltage in the transmission line of the fast linear transformer driver, a compact and self-integrating capacitive sensor is developed. A printed circuit board (PCB) with multi-layer ceramic capacitors (MLCCs) serves as a low-voltage arm. Given the reflow structure of the PCB and a parallel arrangement of MLCCs, the residual inductance of the PCB low-voltage arm can be effectively reduced. Moreover, its capacitance can be easily adjusted. The capacitive sensor is designed using a coaxial structure, suitable for installation on the inner high voltage electrode of the secondary water-insulated transmission line. Three matching schemes for the measuring cable are discussed, showing that two-stage division with matching at the end of the cable is more suitable for fast pulsed voltage measurement due to its high dividing ratio and flat frequency response. A square wave with a rise time of ∼1.5 ns and a pulse width of ∼200 ns is used to verify the properties of the capacitive sensor. The results show that the rise time of the designed capacitive sensor can reach 1.5 ns when a short cable is used. Increasing capacitance of the low-voltage arm or resistance at the cable entrance will increase the time constant of the capacitive sensor, which improves its low-frequency properties. A long cable will significantly reduce the high-frequency response and the magnitude of the signal from the capacitive sensor.