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Analysis of X-ray iron and nickel radiation and jetsfrom planar wire arrays and X-pinchesTo cite this article A S Safronova et al 2010 J Phys Conf Ser 244 032031

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Analysis of X-ray Iron and Nickel Radiation and Jets from Planar Wire arrays and X-pinches

A S Safronova V L Kantsyrev A A Esaulov N D Ouart V Shlyaptseva K M Williamson I Shrestha G C Osborne and M E Weller

University of Nevada Reno NV 89557 USA

E-mail allaunredu

Abstract University-scale Z-pinch devices are able to produce plasmas with a broad range of sizes temperatures densities their gradients and opacity properties Radiative properties of such plasmas depend on material mass and configuration of the wire array loads Experiments with two different types of loads double planar wire arrays (DPWA) and X-pinches performed on the 1 MA Zebra generator at UNR are analyzed X-pinches are made from Stainless Steel (69 Fe 20 Cr and 9 Ni) wires Combined DPWAs consist of one plane from SS wires and another plane from Alumel (95 Ni 2 Al 2 Si) wires The main focus of this work is on the analysis of plasma jets at the early phase of plasma formation and the K- and L-shell radiation generation at the implosion and stagnation phases in experiments with the two aforementioned wire loads The relevant theoretical tools that guide the data analysis include non-LTE collisional-radiative and wire ablation dynamics models The astrophysical relevance of the plasma jets as well as of spectroscopic and imaging studies are demonstrated

1 Introduction It was shown that planar wire arrays (PWA) a new type of the wire array load produced significant radiation yields on a ns-scale particularly DPWAs (up to Et ~ 25 kJ and Ppeak ~ 1 TW) and generated bright spots of sub-mm size [1 2] X-pinches are also very good sources of x-rays and can be used for studying radiative properties of plasmas with even higher electron temperatures (Te gt 2 keV) and densities (Ne gt 1022 cm-3) than that from PWAs on scales of a few microm to several mm in size [1 3-4] They yield short (few ns) x-ray bursts from one or several bright plasma spots near the wire cross point and produce strong electron beams Recently the first applications of X-pinches to astrophysics were proposed and described in [5] Here we present the results of the new experiments with X-pinches focused on the simultaneous study of ldquohotrdquo Heα and ldquocoldrdquo Kα lines of Fe and Ni In general Lyα lines of Fe XXVI and associated satellite lines (and also Ni XXVIII) are the highest temperature lines observed in solar flares [6] Heα lines of Fe XXV and Ni XXVII (~67 keV and ~78 keV respectively) are also indicative of high temperatures (gt15 keV) These are many similarities between solar flare spectra where the ldquohotrdquo Fe lines were observed and studied and the spectra of certain other astrophysical sources such as stellar coronae and supernova remnants Then the study of these lines has broader applications than just for solar flares In addition the ldquocoldrdquo Kα 64 keV iron line provides information on cool material in the vicinity of hard x-ray sources as well as on the characteristics of the x-ray sources themselves and was discovered in the x-ray spectra from the solar flares x-ray binaries and active galactic nuclei The understanding of mechanism of origination of ldquohotrdquo and ldquocoldrdquo Fe lines in various astrophysical objects is very important (see for example [7])

The Sixth International Conference on Inertial Fusion Sciences and Applications IOP PublishingJournal of Physics Conference Series 244 (2010) 032031 doi1010881742-65962443032031

ccopy 2010 IOP Publishing Ltd 1

and can be improved by studying these lines in laboratory plasma under well controlled experimental conditions

2 Experimental results and discussion Experiments with two different types of loads double planar wire arrays (DPWA) and X-pinches were performed on the 1 MA (100 ns current rise time) Zebra generator at UNR X-pinches are made from Stainless Steel (SS 304 69 Fe 20 Cr and 9 Ni) wires Combined DPWAs consist of one plane from SS wires and another plane from Alumel (95 Ni 2 Al 2 Si) wires The experimental diagnostic set includes filtered PCD and XRD detectors laser shadowgraphy x-ray time-gated and time-integrated imaging and time-integrated spatially resolved and time-gated spatially integrated spectrometers for harder (K-shell) and softer (L-shell) x-ray regions Previous studies of SS X-pinches which relied mostly on x-ray diagnostics [15] were expanded here to include shadowgraphy The typical shadowgraphy of explosion of the X-pinch recorded at 50 ns after current start is shown in Fig 1b The typical time-integrated spatially-resolved K-shell spectrum shown in Fig 1c includes both ldquohotrdquo Heα and ldquocoldrdquo Kα lines of Fe Cr and Ni The presence of Heα lines localized in the middle indicates the hot thermal plasmas (Tegt15 keV) innear wire cross-point The ldquocoldrdquo Kα lines spread towards the anode and represent the signatures of much cooler thermal plasmas (lt 100eV) with non-thermal electron beams The use of alloyed SS wires instead of pure Fe wires helps to study simultaneously three different materials in similar plasma conditions and lower opacity effects on spectra due to small concentrations in an original alloy

Figure 1 Stainless Steel X-pinch (shot 1591) a) Load before the shot b) Laser shadow image c) X-ray image of the spatially-resolved spectrum recorded by the LiF crystal (top) and lineout of the time-integrated spatially-resolved spectrum which includes He-like lines of Fe and Cr as well as characteristic ldquocoldrdquo Kα lines of Fe Cr and Ni

The results of the experiment with combined DPWA are shown in Fig 2 The wires ablated very little yet at 14 ns after the current start as it seen on ICCD image (Fig 2c) and predicted by WADM [8] calculations (Fig 2d) Then as ablation progresses faster ablation of Alumel wires results in higher density and lower velocity (up to 100 kms) of the ablation flow and slower ablation of SS wires results in lower density and higher velocity (up to 120 kms) of the ablation flow (Fig 2ef)

The Sixth International Conference on Inertial Fusion Sciences and Applications IOP PublishingJournal of Physics Conference Series 244 (2010) 032031 doi1010881742-65962443032031

2

0

1

2

3

4

5WTh [kJ]

0

02

04

06

08

1I [MA]

0 40 80 120 160t [ns]

Experiment

current

XRD

PCDWADM

WTh

123456

(b) (c) (d)

-2 0 2x [mm]

-4

-2

0

2

4y [mm]

(a)

-3 -2 -1 0 1 2 3

x [mm]

-4

-3

-2

-1

0

1

2

3

4y [m

m]

1E-004 2E-004 3E-004

ρ [gcm3]t = 69 ns t = 76 ns(e) (f) (g) (h)

-2 0 2x [mm]

-4

-2

0

2

4y [mm]

array wiresAlumel

SS

ablatedplasma

Alumel

SS

mixed

t = 72 ns

SSSS

SS

Alumel AlumelAlumel

Figure 2 AlumelStainless Steel DPWA (shot 1774) (a) Load before the shot (side view) (b) Experimental current pulse x-ray detector signals and the positions of MCP for time-gated spectra and thermalized kinetic energy WTh calculated by the WADM (c) ICCD camera image of the load taken at 14 ns (side view perpendicular to wire planes) Positions of array wires and current filaments associated with the ablated plasmas (top view from the anode side) according to the WADM at 14 ns (d) and at 72 ns (e) View direction of ICCD camera is shown by black arrow in plot (d) Contours represent the intensity lines of the global magnetic field (f) 2D mass density distribution of the ablated plasma reconstructed from the WADM simulation at 72 ns An arrow in plot (f) shows the view direction of the laser shadow images (side view along wire planes) recorded at 69 ns (g) and 76 ns (h) Time is referred to the current pulse start

Figure 3 AlumelStainless Steel DPWA (shot 1774) Time-gated spectra images (a) and the spectrum recorded by the MCP frame 4 fit with non-LTE modelling (b)

The Sixth International Conference on Inertial Fusion Sciences and Applications IOP PublishingJournal of Physics Conference Series 244 (2010) 032031 doi1010881742-65962443032031

3

Both plasma jets are supersonic with Mach number ~ 6 (sound speed is ~ 20 kms) The disbalance of velocities of two plasma jets moving from the Alumel and SS sides and resultant 3D hydrodynamic instabilities in high-beta plasma may explain leaning of the precursor plasma column toward the Alumel wire side which is clearly seen on shadowgraphy images taken at 69 and 76 ns after current start (see Fig 2g and h respectively) Although as compared to real astrophysical objects (see for example the discussion in Ref [9]) the dimensional characteristics such as the length time and density are very much different the jet velocities and Mach numbers are well in the range

Four time-gated spectra recorded by MCP frames 3-6 just before and during x-ray burst (see MCP locations in Fig 2b and spectra in Fig 3) are shown in Fig 3a The first three spectra (3-5) before x-ray burst express very small changes in line intensities and hence can be described by similar plasma parameters These spectra include the diagnostically important Ne-like Ni lines (nC and nD) due to transitions from high Rydberg states n=4 and 5 and F-like spectral features between them The synthetic spectrum calculated at Te=400 eV and Ne=5x1019 cm-3 reproduces well the experimental spectra recorded by frames 3-5 (see Fig 3b) The spectrum at the peak of x-ray burst shows more continuum radiation which might indicate the presence of electron beams

3 Conclusion The new results of X-pinch and double planar wire array experiments are presented The wire material was chosen to produce plasmas from astrophysically relevant Fe and Ni ions Plasma jets from X-pinch and in addition from DPWA experiments were observed through laser shadowgraphy The resonance He-like lines of Fe from hot plasmas as well as ldquocoldrdquo Kα lines from much cooler plasma with Fe Cr and Ni neutrals and low-ionized ions were recorded and analyzed

Acknowledgment This work was supported by NNSA under DOE Cooperative Agreements DE-FC52-06NA27588 DE-FC52-06NA27586 and in part by DE-FC52-06NA27616

References [1] Kantsyrev V L Rudakov L I Safronova A S Fedin D A Ivanov V V Velikovich A L Esaulov

A A Chuvatin A S Williamson K Ouart N D Nalajala V Osborne G Shrestha I Yilmaz M F Shivaji P Laca P J and Cowan T E 2006 IEEE Trans Plasma Science 34 194 and 2295

[2] Kantsyrev V L Rudakov L I Safronova A S Esaulov A A Chuvatin A S Coverdale C A Deeney C Williamson K M Yilmaz M F et al 2008 Physics of Plasmas 15 030704

[3] Safronova A Kantsyrev V Ouart N Yilmaz F Fedin D Astanovitsky A LeGalloudec B Batie S Brown D Nalajala V Shrestha I Pokala S Cowan T Jones B Coverdale C Deeney C et al 2006 Journal of Quantitative Spectroscopy and Radiative Transfer 99 560

[4] Safronova A S Kantsyrev V L Neill P Safronova U I Fedin D A Ouart N D Yilmaz M F Osborne G C Shrestha I Williamson K M Hoppe T Harris C Beiersdorfer P and Hansen S 2008 Canadian Journal of Physics 86 267

[5] Safronova A S Kantsyrev V L Esaulov A A Ouart N D Safronova U I Shrestha I and Williamson K M 2009 European Physical Journal Special Topics 169 155

[6] Phillips KJH 2004 The Astrophysical Journal 605 921 [7] Page MJ Soria R Zane S Wu K and Starling RLC 2004 Astronomy and Astrophysics 422 77 [8] Esaulov A A Kantsyrev V L Safronova A S Williamson K M Shrestha I Osborne G C

Yilmaz M F Ouart N D and Weller M E 2009 High Energy Density Physics 5 166 [9] Nicolaiuml Ph Stenz C Kasperczuk A Pisarczyk T Klir D Juha L Krousky E Masek K Pfeifer

M Rohlena K Skala J Tikhonchuk V Ribeyre X Galera S Schurtz G Ullschmied J Kalal M Kravarik J Kubes P et al 2008 Physics of Plasmas 15 082701

The Sixth International Conference on Inertial Fusion Sciences and Applications IOP PublishingJournal of Physics Conference Series 244 (2010) 032031 doi1010881742-65962443032031

4

and can be improved by studying these lines in laboratory plasma under well controlled experimental conditions

2 Experimental results and discussion Experiments with two different types of loads double planar wire arrays (DPWA) and X-pinches were performed on the 1 MA (100 ns current rise time) Zebra generator at UNR X-pinches are made from Stainless Steel (SS 304 69 Fe 20 Cr and 9 Ni) wires Combined DPWAs consist of one plane from SS wires and another plane from Alumel (95 Ni 2 Al 2 Si) wires The experimental diagnostic set includes filtered PCD and XRD detectors laser shadowgraphy x-ray time-gated and time-integrated imaging and time-integrated spatially resolved and time-gated spatially integrated spectrometers for harder (K-shell) and softer (L-shell) x-ray regions Previous studies of SS X-pinches which relied mostly on x-ray diagnostics [15] were expanded here to include shadowgraphy The typical shadowgraphy of explosion of the X-pinch recorded at 50 ns after current start is shown in Fig 1b The typical time-integrated spatially-resolved K-shell spectrum shown in Fig 1c includes both ldquohotrdquo Heα and ldquocoldrdquo Kα lines of Fe Cr and Ni The presence of Heα lines localized in the middle indicates the hot thermal plasmas (Tegt15 keV) innear wire cross-point The ldquocoldrdquo Kα lines spread towards the anode and represent the signatures of much cooler thermal plasmas (lt 100eV) with non-thermal electron beams The use of alloyed SS wires instead of pure Fe wires helps to study simultaneously three different materials in similar plasma conditions and lower opacity effects on spectra due to small concentrations in an original alloy

Figure 1 Stainless Steel X-pinch (shot 1591) a) Load before the shot b) Laser shadow image c) X-ray image of the spatially-resolved spectrum recorded by the LiF crystal (top) and lineout of the time-integrated spatially-resolved spectrum which includes He-like lines of Fe and Cr as well as characteristic ldquocoldrdquo Kα lines of Fe Cr and Ni

The results of the experiment with combined DPWA are shown in Fig 2 The wires ablated very little yet at 14 ns after the current start as it seen on ICCD image (Fig 2c) and predicted by WADM [8] calculations (Fig 2d) Then as ablation progresses faster ablation of Alumel wires results in higher density and lower velocity (up to 100 kms) of the ablation flow and slower ablation of SS wires results in lower density and higher velocity (up to 120 kms) of the ablation flow (Fig 2ef)

The Sixth International Conference on Inertial Fusion Sciences and Applications IOP PublishingJournal of Physics Conference Series 244 (2010) 032031 doi1010881742-65962443032031

2

0

1

2

3

4

5WTh [kJ]

0

02

04

06

08

1I [MA]

0 40 80 120 160t [ns]

Experiment

current

XRD

PCDWADM

WTh

123456

(b) (c) (d)

-2 0 2x [mm]

-4

-2

0

2

4y [mm]

(a)

-3 -2 -1 0 1 2 3

x [mm]

-4

-3

-2

-1

0

1

2

3

4y [m

m]

1E-004 2E-004 3E-004

ρ [gcm3]t = 69 ns t = 76 ns(e) (f) (g) (h)

-2 0 2x [mm]

-4

-2

0

2

4y [mm]

array wiresAlumel

SS

ablatedplasma

Alumel

SS

mixed

t = 72 ns

SSSS

SS

Alumel AlumelAlumel

Figure 2 AlumelStainless Steel DPWA (shot 1774) (a) Load before the shot (side view) (b) Experimental current pulse x-ray detector signals and the positions of MCP for time-gated spectra and thermalized kinetic energy WTh calculated by the WADM (c) ICCD camera image of the load taken at 14 ns (side view perpendicular to wire planes) Positions of array wires and current filaments associated with the ablated plasmas (top view from the anode side) according to the WADM at 14 ns (d) and at 72 ns (e) View direction of ICCD camera is shown by black arrow in plot (d) Contours represent the intensity lines of the global magnetic field (f) 2D mass density distribution of the ablated plasma reconstructed from the WADM simulation at 72 ns An arrow in plot (f) shows the view direction of the laser shadow images (side view along wire planes) recorded at 69 ns (g) and 76 ns (h) Time is referred to the current pulse start

Figure 3 AlumelStainless Steel DPWA (shot 1774) Time-gated spectra images (a) and the spectrum recorded by the MCP frame 4 fit with non-LTE modelling (b)

The Sixth International Conference on Inertial Fusion Sciences and Applications IOP PublishingJournal of Physics Conference Series 244 (2010) 032031 doi1010881742-65962443032031

3

Both plasma jets are supersonic with Mach number ~ 6 (sound speed is ~ 20 kms) The disbalance of velocities of two plasma jets moving from the Alumel and SS sides and resultant 3D hydrodynamic instabilities in high-beta plasma may explain leaning of the precursor plasma column toward the Alumel wire side which is clearly seen on shadowgraphy images taken at 69 and 76 ns after current start (see Fig 2g and h respectively) Although as compared to real astrophysical objects (see for example the discussion in Ref [9]) the dimensional characteristics such as the length time and density are very much different the jet velocities and Mach numbers are well in the range

Four time-gated spectra recorded by MCP frames 3-6 just before and during x-ray burst (see MCP locations in Fig 2b and spectra in Fig 3) are shown in Fig 3a The first three spectra (3-5) before x-ray burst express very small changes in line intensities and hence can be described by similar plasma parameters These spectra include the diagnostically important Ne-like Ni lines (nC and nD) due to transitions from high Rydberg states n=4 and 5 and F-like spectral features between them The synthetic spectrum calculated at Te=400 eV and Ne=5x1019 cm-3 reproduces well the experimental spectra recorded by frames 3-5 (see Fig 3b) The spectrum at the peak of x-ray burst shows more continuum radiation which might indicate the presence of electron beams

3 Conclusion The new results of X-pinch and double planar wire array experiments are presented The wire material was chosen to produce plasmas from astrophysically relevant Fe and Ni ions Plasma jets from X-pinch and in addition from DPWA experiments were observed through laser shadowgraphy The resonance He-like lines of Fe from hot plasmas as well as ldquocoldrdquo Kα lines from much cooler plasma with Fe Cr and Ni neutrals and low-ionized ions were recorded and analyzed

Acknowledgment This work was supported by NNSA under DOE Cooperative Agreements DE-FC52-06NA27588 DE-FC52-06NA27586 and in part by DE-FC52-06NA27616

References [1] Kantsyrev V L Rudakov L I Safronova A S Fedin D A Ivanov V V Velikovich A L Esaulov

A A Chuvatin A S Williamson K Ouart N D Nalajala V Osborne G Shrestha I Yilmaz M F Shivaji P Laca P J and Cowan T E 2006 IEEE Trans Plasma Science 34 194 and 2295

[2] Kantsyrev V L Rudakov L I Safronova A S Esaulov A A Chuvatin A S Coverdale C A Deeney C Williamson K M Yilmaz M F et al 2008 Physics of Plasmas 15 030704

[3] Safronova A Kantsyrev V Ouart N Yilmaz F Fedin D Astanovitsky A LeGalloudec B Batie S Brown D Nalajala V Shrestha I Pokala S Cowan T Jones B Coverdale C Deeney C et al 2006 Journal of Quantitative Spectroscopy and Radiative Transfer 99 560

[4] Safronova A S Kantsyrev V L Neill P Safronova U I Fedin D A Ouart N D Yilmaz M F Osborne G C Shrestha I Williamson K M Hoppe T Harris C Beiersdorfer P and Hansen S 2008 Canadian Journal of Physics 86 267

[5] Safronova A S Kantsyrev V L Esaulov A A Ouart N D Safronova U I Shrestha I and Williamson K M 2009 European Physical Journal Special Topics 169 155

[6] Phillips KJH 2004 The Astrophysical Journal 605 921 [7] Page MJ Soria R Zane S Wu K and Starling RLC 2004 Astronomy and Astrophysics 422 77 [8] Esaulov A A Kantsyrev V L Safronova A S Williamson K M Shrestha I Osborne G C

Yilmaz M F Ouart N D and Weller M E 2009 High Energy Density Physics 5 166 [9] Nicolaiuml Ph Stenz C Kasperczuk A Pisarczyk T Klir D Juha L Krousky E Masek K Pfeifer

M Rohlena K Skala J Tikhonchuk V Ribeyre X Galera S Schurtz G Ullschmied J Kalal M Kravarik J Kubes P et al 2008 Physics of Plasmas 15 082701

The Sixth International Conference on Inertial Fusion Sciences and Applications IOP PublishingJournal of Physics Conference Series 244 (2010) 032031 doi1010881742-65962443032031

4

0

1

2

3

4

5WTh [kJ]

0

02

04

06

08

1I [MA]

0 40 80 120 160t [ns]

Experiment

current

XRD

PCDWADM

WTh

123456

(b) (c) (d)

-2 0 2x [mm]

-4

-2

0

2

4y [mm]

(a)

-3 -2 -1 0 1 2 3

x [mm]

-4

-3

-2

-1

0

1

2

3

4y [m

m]

1E-004 2E-004 3E-004

ρ [gcm3]t = 69 ns t = 76 ns(e) (f) (g) (h)

-2 0 2x [mm]

-4

-2

0

2

4y [mm]

array wiresAlumel

SS

ablatedplasma

Alumel

SS

mixed

t = 72 ns

SSSS

SS

Alumel AlumelAlumel

Figure 2 AlumelStainless Steel DPWA (shot 1774) (a) Load before the shot (side view) (b) Experimental current pulse x-ray detector signals and the positions of MCP for time-gated spectra and thermalized kinetic energy WTh calculated by the WADM (c) ICCD camera image of the load taken at 14 ns (side view perpendicular to wire planes) Positions of array wires and current filaments associated with the ablated plasmas (top view from the anode side) according to the WADM at 14 ns (d) and at 72 ns (e) View direction of ICCD camera is shown by black arrow in plot (d) Contours represent the intensity lines of the global magnetic field (f) 2D mass density distribution of the ablated plasma reconstructed from the WADM simulation at 72 ns An arrow in plot (f) shows the view direction of the laser shadow images (side view along wire planes) recorded at 69 ns (g) and 76 ns (h) Time is referred to the current pulse start

Figure 3 AlumelStainless Steel DPWA (shot 1774) Time-gated spectra images (a) and the spectrum recorded by the MCP frame 4 fit with non-LTE modelling (b)

The Sixth International Conference on Inertial Fusion Sciences and Applications IOP PublishingJournal of Physics Conference Series 244 (2010) 032031 doi1010881742-65962443032031

3

Both plasma jets are supersonic with Mach number ~ 6 (sound speed is ~ 20 kms) The disbalance of velocities of two plasma jets moving from the Alumel and SS sides and resultant 3D hydrodynamic instabilities in high-beta plasma may explain leaning of the precursor plasma column toward the Alumel wire side which is clearly seen on shadowgraphy images taken at 69 and 76 ns after current start (see Fig 2g and h respectively) Although as compared to real astrophysical objects (see for example the discussion in Ref [9]) the dimensional characteristics such as the length time and density are very much different the jet velocities and Mach numbers are well in the range

Four time-gated spectra recorded by MCP frames 3-6 just before and during x-ray burst (see MCP locations in Fig 2b and spectra in Fig 3) are shown in Fig 3a The first three spectra (3-5) before x-ray burst express very small changes in line intensities and hence can be described by similar plasma parameters These spectra include the diagnostically important Ne-like Ni lines (nC and nD) due to transitions from high Rydberg states n=4 and 5 and F-like spectral features between them The synthetic spectrum calculated at Te=400 eV and Ne=5x1019 cm-3 reproduces well the experimental spectra recorded by frames 3-5 (see Fig 3b) The spectrum at the peak of x-ray burst shows more continuum radiation which might indicate the presence of electron beams

3 Conclusion The new results of X-pinch and double planar wire array experiments are presented The wire material was chosen to produce plasmas from astrophysically relevant Fe and Ni ions Plasma jets from X-pinch and in addition from DPWA experiments were observed through laser shadowgraphy The resonance He-like lines of Fe from hot plasmas as well as ldquocoldrdquo Kα lines from much cooler plasma with Fe Cr and Ni neutrals and low-ionized ions were recorded and analyzed

Acknowledgment This work was supported by NNSA under DOE Cooperative Agreements DE-FC52-06NA27588 DE-FC52-06NA27586 and in part by DE-FC52-06NA27616

References [1] Kantsyrev V L Rudakov L I Safronova A S Fedin D A Ivanov V V Velikovich A L Esaulov

A A Chuvatin A S Williamson K Ouart N D Nalajala V Osborne G Shrestha I Yilmaz M F Shivaji P Laca P J and Cowan T E 2006 IEEE Trans Plasma Science 34 194 and 2295

[2] Kantsyrev V L Rudakov L I Safronova A S Esaulov A A Chuvatin A S Coverdale C A Deeney C Williamson K M Yilmaz M F et al 2008 Physics of Plasmas 15 030704

[3] Safronova A Kantsyrev V Ouart N Yilmaz F Fedin D Astanovitsky A LeGalloudec B Batie S Brown D Nalajala V Shrestha I Pokala S Cowan T Jones B Coverdale C Deeney C et al 2006 Journal of Quantitative Spectroscopy and Radiative Transfer 99 560

[4] Safronova A S Kantsyrev V L Neill P Safronova U I Fedin D A Ouart N D Yilmaz M F Osborne G C Shrestha I Williamson K M Hoppe T Harris C Beiersdorfer P and Hansen S 2008 Canadian Journal of Physics 86 267

[5] Safronova A S Kantsyrev V L Esaulov A A Ouart N D Safronova U I Shrestha I and Williamson K M 2009 European Physical Journal Special Topics 169 155

[6] Phillips KJH 2004 The Astrophysical Journal 605 921 [7] Page MJ Soria R Zane S Wu K and Starling RLC 2004 Astronomy and Astrophysics 422 77 [8] Esaulov A A Kantsyrev V L Safronova A S Williamson K M Shrestha I Osborne G C

Yilmaz M F Ouart N D and Weller M E 2009 High Energy Density Physics 5 166 [9] Nicolaiuml Ph Stenz C Kasperczuk A Pisarczyk T Klir D Juha L Krousky E Masek K Pfeifer

M Rohlena K Skala J Tikhonchuk V Ribeyre X Galera S Schurtz G Ullschmied J Kalal M Kravarik J Kubes P et al 2008 Physics of Plasmas 15 082701

The Sixth International Conference on Inertial Fusion Sciences and Applications IOP PublishingJournal of Physics Conference Series 244 (2010) 032031 doi1010881742-65962443032031

4

Both plasma jets are supersonic with Mach number ~ 6 (sound speed is ~ 20 kms) The disbalance of velocities of two plasma jets moving from the Alumel and SS sides and resultant 3D hydrodynamic instabilities in high-beta plasma may explain leaning of the precursor plasma column toward the Alumel wire side which is clearly seen on shadowgraphy images taken at 69 and 76 ns after current start (see Fig 2g and h respectively) Although as compared to real astrophysical objects (see for example the discussion in Ref [9]) the dimensional characteristics such as the length time and density are very much different the jet velocities and Mach numbers are well in the range

Four time-gated spectra recorded by MCP frames 3-6 just before and during x-ray burst (see MCP locations in Fig 2b and spectra in Fig 3) are shown in Fig 3a The first three spectra (3-5) before x-ray burst express very small changes in line intensities and hence can be described by similar plasma parameters These spectra include the diagnostically important Ne-like Ni lines (nC and nD) due to transitions from high Rydberg states n=4 and 5 and F-like spectral features between them The synthetic spectrum calculated at Te=400 eV and Ne=5x1019 cm-3 reproduces well the experimental spectra recorded by frames 3-5 (see Fig 3b) The spectrum at the peak of x-ray burst shows more continuum radiation which might indicate the presence of electron beams

3 Conclusion The new results of X-pinch and double planar wire array experiments are presented The wire material was chosen to produce plasmas from astrophysically relevant Fe and Ni ions Plasma jets from X-pinch and in addition from DPWA experiments were observed through laser shadowgraphy The resonance He-like lines of Fe from hot plasmas as well as ldquocoldrdquo Kα lines from much cooler plasma with Fe Cr and Ni neutrals and low-ionized ions were recorded and analyzed

Acknowledgment This work was supported by NNSA under DOE Cooperative Agreements DE-FC52-06NA27588 DE-FC52-06NA27586 and in part by DE-FC52-06NA27616

References [1] Kantsyrev V L Rudakov L I Safronova A S Fedin D A Ivanov V V Velikovich A L Esaulov

A A Chuvatin A S Williamson K Ouart N D Nalajala V Osborne G Shrestha I Yilmaz M F Shivaji P Laca P J and Cowan T E 2006 IEEE Trans Plasma Science 34 194 and 2295

[2] Kantsyrev V L Rudakov L I Safronova A S Esaulov A A Chuvatin A S Coverdale C A Deeney C Williamson K M Yilmaz M F et al 2008 Physics of Plasmas 15 030704

[3] Safronova A Kantsyrev V Ouart N Yilmaz F Fedin D Astanovitsky A LeGalloudec B Batie S Brown D Nalajala V Shrestha I Pokala S Cowan T Jones B Coverdale C Deeney C et al 2006 Journal of Quantitative Spectroscopy and Radiative Transfer 99 560

[4] Safronova A S Kantsyrev V L Neill P Safronova U I Fedin D A Ouart N D Yilmaz M F Osborne G C Shrestha I Williamson K M Hoppe T Harris C Beiersdorfer P and Hansen S 2008 Canadian Journal of Physics 86 267

[5] Safronova A S Kantsyrev V L Esaulov A A Ouart N D Safronova U I Shrestha I and Williamson K M 2009 European Physical Journal Special Topics 169 155

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The Sixth International Conference on Inertial Fusion Sciences and Applications IOP PublishingJournal of Physics Conference Series 244 (2010) 032031 doi1010881742-65962443032031

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