Experimental study of Rayleigh Taylor instability by means of magnetic implosion Azra, A.; Baclet, P.; Buchet, J. ...
PPPS-2001 Pulsed Power Plasma Science 2001. 28th IEEE International Conference on Plasma Science and 13th IEEE International Pulsed Power Conference. Digest of Papers (Cat. No.01CH37251),
2001, Volume:
1
Conference Proceeding
Rayleigh-Taylor instability (RTI) in imploding devices is to be studied if to define ICF targets. Direct use of explosive as a propellant was tested by the past to analyse RTI effects. Drawbacks of ...corresponding devices are well known: side effects, high areal masses inducing accuracy limitation in transverse radiographic observation, no simple way for pressure level modulation. They can be avoided by the use of magnetic driver and relevant device design, hereafter described. This paper presents results of a joint CEA/VNIIEF experiment dedicated to this topic. Potok type EMG with FOS was used to provide 7-8 MA current law within a few microseconds. Electrical power supply was provided by VNIIEF, target with diagnostics by CEA.
Experimental study of conical liner magnetic implosion [pulsed power technology] Carlotti, X.; Desanlis, T.; Endignoux, L. ...
PPPS-2001 Pulsed Power Plasma Science 2001. 28th IEEE International Conference on Plasma Science and 13th IEEE International Pulsed Power Conference. Digest of Papers (Cat. No.01CH37251),
2001, Volume:
1
Conference Proceeding
Conical aluminium liner magnetic implosion, focalization on axis and subsequent high velocity matter emission were analysed through a VNIIEF/CEA joint experiment realized in Sarov. The experiment ...results are described in the present paper. Liner focalization and jet formation were to be analyzed through radiographic transverse observation. X-ray flashes were realized at expected two times values, which were only distant by 400 ns. The pictures quality is excellent. This experiment was a challenge both for generator performance (achieve high value of current in EMG and ability to transfer it to chamber) and for hydrodynamical purpose (first flight of conical liner and focalization to axis). For such a new and complex topic, experimental results exhibit very nice agreement with prediction calculations.
The structures of hydrated phosphoric acid and phosphate ions (H2PO4 –, HPO4 2–, and PO4 3–) in aqueous solution have been determined by P K-edge EXAFS and large angle X-ray scattering (LAXS). The ...P–O bond distance in all phosphate species studied is close to 1.53 Å. The P–(O)···Oaq distances have been refined to ca. 3.6 Å from the LAXS data giving a P–O···Oaq bond angle close to tetrahedral, suggesting that each oxygen or OH group of phosphoric acid and dihydrogen phosphate, on average, hydrogen bind three water molecules. The (P−)O(−H)···Oaq and (P−)O···(H−)Oaq hydrogen bonds in hydrated phosphoric acid and the H2PO4 – ion are shorter than the hydrogen bonds in neat water. This supports previous infrared spectroscopic studies claiming that the hydrogen bonds in hydrated phosphoric acid and phosphate ions are stronger than the hydrogen bonds in neat water. Phosphoric acid and phosphate ions can therefore be regarded as structure making solutes. This is the first study applying transmission mode X-ray absorption spectroscopy (XAS) data collection on the P K-edge. It shows that XAS spectra collected in transmission mode have a much better S/N ratio than data collected in fluorescence mode, allowing accurate determination of P–O bond distances. Furthermore, P K-edge EXAFS data collected in fluorescence mode display a higher amplitude at high k than expected due to increasing radiated volume of the sample with increasing energy as the total absorption decreases sharply with increasing energy of the X-rays. As a result, the fluorescence signal becomes nonproportional to the intensity of the X-ray beam over the EXAFS spectrum. This results in an increasing amplitude of the EXAFS function with increasing energy of the X-ray beam resulting in too small Debye–Waller coefficients.
Sorption fixed-bed column experiments were performed using a titanium phosphate ion-exchanger composed of −H2PO4 units TiO(OH)(H2PO4)·H2O. Model mine water containing five divalent metal ions ...(Cu2+, Zn2+, Mn2+, Ni2+, and Co2+) and a few closed-mine water samples were treated to evaluate the sorption preference of the material. For the first time, dynamic ion-exchange capacities (estimated to be between 3.2 and 4.2 mequiv g–1) and static ion-exchange uptakes (calculated to be between 3.1 and 3.5 mequiv g–1) were obtained for the same TiP1 sorbent and data were discussed in terms of sorption behavior. It was found that sorption processes on TiP1 in model and closed-mine waters during a column experiment could be accurately predicted from the corresponding batch experiment (including the sorbent’s capacities in different types of waters). A competitive sorption phenomenon in favor of Cu2+ on TiP1 was established for all cases, pointing toward the possibility of isolating pure copper concentrate from closed-mine waters. The relatively high amounts of calcium and magnesium ions present in mine waters did not appear to considerably affect the selectivity of TiP1 material. Exploratory experiments for sorbent regeneration and desorption using a low concentration of nitric acid were demonstrated.
A titanium phosphate sorbent with linked active units (LTP) is synthesized. XRD, 31P MAS NMR, and TGA techniques are used to disclose the relation between the ion-exchange units of −HPO4 (crystalline ...α-TiP) and of −H2PO4 (amorphous TiP1) type. The reported kinetics data of TiP1 sorbent in batch mode have been reprocessed according to the nonlinear approach in order to explore further the sorption mechanism. It was found that the data could be well described by the pseudo-second-order model in the case of Ni2+ ions. Consequently, fixed-bed column sorption experiments of Ni2+ ions on LTP were designed, and the effects of both the amount of nickel(II) ions in the feed solution and the flow rates on the sorption equilibrium were studied. The ion-exchange capacity is estimated to be 1.6 meq·g–1 during the first four cycles before decreasing to 1.2 meq·g–1 for cycles five and six. The experimental data were simulated following the Thomas model, and desorption experiments with HCl were performed. Observations show that regeneration and reutilization of the LTP ion-exchanger are possible through at least six cycles. It is revealed that the sorption performances in column conditions could be undoubtedly predicted from the corresponding batch sorption data.
This work focuses on the synthesis of titanium phosphate (TiP1) ion-exchanger containing solely H2PO4-groups. Based on the elemental analyses, TG, 31P MAS NMR, XRD and Raman data, the formula ...TiO(OH)(H2PO4)·H2O is assigned to TiP1. The synthesis requires a mild heating at 70–80 °C for a short period of time, followed by filtration and HCl-washing of the TiP1 powder. The layered nature and low crystallinity of this sorbent is confirmed by powder XRD technique. The existence of micro and mesopores in the material is established using BET method. The Na+ capacity of TiP1 is determined to be 6.3 meq g−1 which is the highest value reported for H2PO4-based sorbents. The presence of H2PO4 groups is expected to considerably increase both the pH-working range of the TiP1 sorbent and its exchange capacity towards divalent metal ions. All data for TiP1 are compared to the data for amorphous TiP containing mostly HPO4 groups.
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•TiOSO4/CoSO4/H3PO4 – Synthetic liquor.•Influence of Co2+ ions on the TiO(OH)(H2PO4)·H2O surface characteristics and porosity•H2PO4-based ion-exchanger with a Na+ capacity of 6.3 meq g−1.
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