El Moussati, S.

Hoffmann, D. H. H.

Ionita, B. F.

Kantsyrev, A.

Lang, P. M.

Markov, N.

Nikolaev, D.

Shestov, L.

Shilkin, N.

Ternovoi, V.

Udrea, S.

Varentsov, D.

Weyrich, K.

GSI Repository

GSITemplate2007 Imaging Interferometer for Pressure Measurements in Ion-Beam Driven HEDP Experiments* B.F. Ionita1, S. El Moussati1, D.H.H. Hoffmann1, P.M. Lang1, L. Shestov1, S. Udrea1, D. Varentsov2, K. Weyrich2, D. Nikolaev3, N. Shilkin3, V. Ternovoi3, A. Kantsyrev4, and N. Markov4  1TUD, Darmstadt, Germany; 2GSI, Darmstadt, Germany; 3IPCP, Chernogolovka, Russia; 4ITEP, Moscow, RussiaThe relatively poorly explored near critical region of Pb (Tc ≈ 5500 K, pc ≈ 2.3 kbar) was reached at HHT using sub-microsecond SIS-18 uranium beams at 350 AMeV and ~3·109 particles/pulse, with a sub-millimetre spot on target, leading to uniform isochoric heating, evaporation and expansion of the material across a gap (Fig. 1a).    Figure 1: Target - ion beam - diagnostics configuration: (a) experimental principle; (b) target holder.  The behaviour of Pb during isentropic compression on the front surface of a sapphire window (Fig. 1) was analyzed using a fast multi-channel pyrometer [1] and a specially developed imaging displacement interferometer (Fig. 2), designed to permit for the first time simultaneous temperature and pressure measurements (Fig. 3) by integrating the light collection optics for both systems on the pyrometer head. The specularly reflecting sapphire surface is imaged on a 50% beam-splitter through a doubly afocal system in order to keep the optical front flat. It is further relayed to the surface of the reference mirror which can be tilted remotely to allow for fringe tuning, and to an alignment camera and a streak camera, at a final resolution of ~50 µm. The imaging capability is used to solve fringe movement uncertainties.   Figure 2: Optical schematics of the diagnostic devices.  Pressure is calculated as the product of acoustic impedance of sapphire and particle velocity (half of the surface velocity obtained through time derivation of the measured displacement, given no impedance matching).  Figure 3: Simultaneous temperature (red), pressure (blue) and ion beam intensity (black) temporal profiles.   Figure 4: Explored region of the T-P phase diagram.  Two obtained temperature-pressure curves are shown in Fig. 4, as they start from a point on the boiling curve, approximately follow the 3.7 Mbar release isentrope [3] until it intersects the spinodal curve, afterwards kinematic effects govern the dynamics of the superheated material, to finally reach an area near the boiling curve. Using higher intensities up to ~5·1011 particles/pulse available at FAIR, the near critical region of other metals, especially refractory ones (e.g. Ta, Ti, W) can be probed. References [1] P. Ni et al., Las. Part. Beams 26 (04), 583 (2008). [2] D. Varentsov et al., Nucl. Instrum. Meth. Phys. Res. A 577, 262 (2007). [3] V. Ternovoi et al., in Physics of Strongly Coupled Plasmas, eds. W.D. Kraeft et al., World Scientific Publishing Ltd, Singapore, 1996, pp.119-124. (a) (b) * Work supported by Helmholtz-Russia Joint Research  Group HRJRG-112 and BMBF 06DA9033I. PNI-INHOUSE-EXP-08 GSI SCIENTIFIC REPORT 2012376

Imaging Interferometer for Pressure Measurements in Ion-Beam  Driven HEDP Experiments

http://repository.gsi.de/record/52269/files/PNI-INHOUSE-EXP-08.pdf

Imaging Interferometer for Pressure Measurements in Ion-Beam Driven HEDP Experiments

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