23rd September, 2017Czech Republic, Prague

Time-integrated optical and extreme ultraviolet emission studies of the laser produced neon and nitrogen plasmas

Ismail Saber

Home University: Military University of Technology, WarsawSupervisor: Dr. Andrzej Bartnik

Host University: Czech Technical University in Prague, PragueSupervisor: Prof. J. Limpouch

Outline• Motivation and aims • Experimental setup and theoretical simulations• Results of investigations• Summary and outlook

Motivation• Plasmas can be produced by photoionization of atomic and molecular

gases with the use of intense EUV nanosecond pulses• Spectral investigations of plasmas provide information about the kinetics

and plasma parameters• Research on photoionized plasmas is applicable in astrophysics and

technologyAims• To study atomic processes in photoionized

plasmas created by LPP EUV/SXR sources.• Estimate basic plasma parameters, Te& ne

MOTIVATION AND AIMS

N2

EUV

He

EUV

Laser plasma EUV source driven by a 10 J/10 ns/10 Hz Nd:YAG laser

UV/VIS spectrometer• An Echelle Spectra Analyzer (ESA 4000)• Spectral range: 200-780 nm• Spectral resolution: λ/∆λ ≈20000

Ineraction chamberNd:YAG laser

Schematic view and Experimental source First source

Scheme of the Multifoil EUV collector

Vacuum chamber

http://www.lla-instruments.comA. Bartnik et al. Phy. Scr. T161, 014061 (2014)

EUV source

EUV Spectrometer

EUV spectrometer• a grazing incidence flat-field

spectrometer (McPherson, Model 251). • Grating: 450 lines/mm • Wavelength range: 10-95 nm, • Spectral resolution λ/∆λ ≈ 500EUV intensity

107 - 108 W/cm2

Laser plasma EUV sourcedriven by a 0.8 J/4 ns/10 Hz Nd:YAG laser

Schematic view and Experimental source Second source

He

N2 /Ar

He

N2 /Ar

Gas Puff-target

Selected Results

0

9500

19000

28500

38000

47500

57000

240 300 360 420 480 540 600 660 720 780

Inte

nsity

(arb

. uni

ts)

Wavelength (nm)

Measured

H

Non-LTE calculation, PrismSPECT

Te = 1.99 eVne = 2cm-3

Measured and simulated emission spectra of Ne photoionized plasma

The intense spectral lines were from Ne I and Ne II ions

Emission lines of Ne I-IV were detected with relatively low

intensity comparing to neutral and single charged ions

Accumulated 10 pulsesIntegrated over 3ns, 5.6 J

580 590 600 610 620 630 640 650 6600

960

1920

2880

3840

4800

5760

6720

Ne I

2p5 3s

2 [1/2

]0 - 2p5 3p

2 [1/2

]

2p5 3s

2 [3/2

]0 - 2p5 3p

2 [5/2

]

2p5 3s

2 [3/2

]0 - 2p5 3p

2 [5/2

]

2p5 3s

2 [1/2

]0 - 2p5 3p

2 [3/2

]

2p5 3s

2 [1/2

]0 - 2p5 3p

2 [1/2

]

2p5 3s

2 [3/2

]0 - 2p5 3p

2 [3/2

]

2p5 3s

2 [3/2

]0 - 2p5 3p

2 [3/2

]

2p5 3s

2 [3/2

]0 - 2p5 3p

2 [1/2

]

2p5 3s

2 [3/2

]0 - 2p5 3p

2 [3/2

]

2p5 3s

2 [3/2

]0 - 2p5 3p

2 [3/2

]

2p5 3s

2 [3/2

]0 - 2p5 3p

2 [1/2

]

2p5 3s

2 [1/2

]0 - 2p5 3p

2 [1/2

]

Inte

nsity

(arb

. uni

ts)

Wavelength (nm)

Emission spectra emitted from Ne I in the visible range

Results Continue…

All emission lines corresponding to the spectral lines of atomic neon

Results Continue…

360 364 368 372 376 3800

1000

2000

3000

330 332 334 336 338 3400

1000200030004000

340 344 348 352 356 3600

500100015002000

3s -

3p (2 P 3/

2 - 2 P0 3/

2)

3s -

3p (4 P 1/

2 - 4 P0 3/

2)

3s -

3p (4 P 3/

2 - 4 P0 5/

2)

3s -

3p (2 P 1/

2 - 2 D

0 3/2)

3s -

3p (2 P 3/

2 - 2 D

0 5/2)

3s -

3p (4 P 3/

2 - 4 P0 1/

2)

3s -

3p (4 P 5/

2 - 4 P0 5/

2)

3s -

3p (4 P 5/

2 - 4 P0 3/

2)

3s -

3p (2 P 3/

2 - 2 D

0 3/2)

Inte

nsity

(arb

. uni

ts)

Wavelength (nm)

Ne II

3s -

3p (2 P 1/

2 - 2 P0 3/

2)

3p -

3d (2 D

0 3/2 -

2 F 5/2)

3s -

3p (2 P 1/

2 - 2 P0 1/

2)

3p -

3d (2 D

0 5/2 -

4 F 7/2)

3s -

3p (4 P 1/

2 - 4 D

0 3/2)

3s -

3p (4 P 3/

2 - 4 D

0 5/2)

3s -

3p (2 D

5/2 -

2 P0 3/2)

3s -

3p (4 P 1/

2 - 4 D

0 1/2)

3s -

3p (4 P 5/

2 - 4 D

0 7/2)

3p -

3d (4 D

0 7/2 -

4 D7/

2)

3s -

3p (4 P 3/

2 - 2 D

0 3/2)

3s -

3p (2 P 3/

2 - 2 P0 3/

2)

3s -

3p (2 D

3/2 -

2 P0 1/2)

3s -

3p (2 P 3/

2 - 2 P0 1/

2)

3p -

3d (2 S0 1/

2 - 2 P 1/

2)

? 3p -

3d (4 S0 3/

2 - 4 P 1/

2)

?

?

3s -

3p (2 D

3/2 -

2 F0 5/2)

3s -

3p (2 D

5/2 -

2 F0 7/2)

3p -

3d (4 S0 3/

2 - 4 P 5/

2)

3p -

3d (4 S0 3/

2 - 2 P 1/

2)

3s -

3p (2 P 3/

2 - 2 S0 1/

2)

3p -

3d (2 D

0 5/2 -

2 D5/

2)

3p -

3d (2 S0 1/

2 - 2 P 3/

2)

3p -

3d (2 D

0 5/2 -

2 F 7/2)

3p -

3d (2 D

0 5/2 -

2 D5/

2)

Part of emission spectra observed in the ultraviolet region of Ne II

30 32 34 36 38

-14

-13

-12

-11

-10

ln(i ki

ki/g

kA ki)

Ek (eV)

Ne IITe = 1.8 0.02 eV

18.4 18.8 19.2 19.6 20.0

-5.0

-4.5

-4.0

-3.5

-3.0

-2.5

-2.0

ln(I ki ki

/gkA

ki

Ek (eV)

Ne ITe = 0.66 0.09 eV

Results Continue…

Boltzmann plot utilizing Ne II ionic linesBoltzmann plot utilizing neutral lines

The slope of the best fit straight line indicated temperature of 1.8 eV in Ne II and almost 0.7 eV in Ne I

Spectra of gases ionized with EUV radiation pulses from a laser-plasma source: Neon

Ne, EUV 100 pulsesP=5bar, PW=300 µs

Submitted to Proceeding of The 15th International Conf. on X-Ray Lasers, Japan

Results Continue…

LTE approximation

25 30 35 40 45 50 55 60

2s2 2p

5 - 2s2

p6

Inte

nsity

(arb

.uni

ts)

Experiment

2s2 2p

4 - 2s2

p5

2s2 2p

5 - 2s2 2p

4 (1 D)3

d, (1 D

)4s

2s2 2p

5 - 2s2 2p

4 (3 P)4

d

2s2 2p

5 - 2s

2 2p4 (3 P

)3d

2s2 2p

5 - 2s2 2p

4 (1 S)3s

2s2 2p

5 - 2s2 2p

4 (1 D)3

s

2s2 2p

5 - 2s2 2p

4 (3 P)3s

Ne IIINe II

Wavelength (nm)

PrismSPECTTe = 1.95 eV

ne = 5x1015 cm-3

The most intense emission lines were assigned to singly charged ions.

The other emission lines belong to doubly ionized ions or neutral atoms

Mostly, thespectrallines correspondingto

2푠 2푝 푛푙 − 2푠 2푝 푛푙transitions

0 10 20 30 40 50 60 700

10

20

30

40

50

0 10 20 30 40 50 60 700

5

10

15

20

25

30

35

40

0 10 20 30 40 50 60 700

2

4

6

8

10

12

0 10 20 30 40 50 60 700

2

4

6

8

10

Ne III

35.8

0 nm

32.6

7 nm

40.7

1 nm

44.6

2 nm

46.0

7 nm

Ne II

Inte

nsity

(arb

. uni

ts)

Wavelength (nm)

Ne, 5bar, 350s E = 5.5J, 10 shot T = -40C ADCx4 BS

Inte

nsity

(arb

. uni

ts)

Wavelength (nm)

Ne, 5bar, 350s E = 4.6J,10 shot T = -40C ADCx4

Inte

nsity

(arb

. uni

ts)

Wavelength (nm)

NeKr, 5bar, 350s E = 5.5J, 10 shot T = -60C ADCx4 BS

Inte

nsity

(arb

. uni

ts)

Wavelength (nm)

NeKr, 5bar, 350s E = 5.4J,10 shot T = -60 C ADCx4 BS

EUV spectrum of Ne ions

The spectra dominated by 2s22p5

2P03/2 - 2s22p43s,2P3/2

transitions Significant decreased in intensity

at presents of Kr gas

Results Continue…

eBe

ikeik Tk

EkTE

gfexp106.1 2/1

5

The excitation rate coefficient 휎 푣 can be calculated as*

* H.J. Kunze, Space Sci. Rev. 13, 565 (1972)** J. D. Hey, J. Quant. Spectrosc. Radiat. Transf. 16, 69 (1976)

Examination of excitation and radiative rates in plasma: To clarify the LTE condition

Results Continue…

• 휎 푣 represents coefficient rate of excitation• fik is represents the absorption oscillator strength • 푔 is effective grant factor averaged over all Maxwellian velocity distribution function. • ΔE (in eV) is the energy difference between the states and • kB and Te are respecrively the Boltzmann constant and plasma electron temperature

eik

The electron impact excitation rate is given by**푆 = 푛 휎 푣

NeII333.484nm, 2푠 2푝 3푠4푃 / − 2푠 2푝 3푝4퐷 /

NeII356.585nm, 2푠 2푝 3푝4푆 / − 2푠 2푝 3푑4푃 /

NeII371.313nm, 2푠 2푝 3푠2푃 / − 2푠 2푝 3푝2퐷 /

NeI584.258nm, 2푠 2푝 3푠2[1/2] −2푠 2푝 3푝2[1/2]

NeI588.189푛푚, 2푠 2푝 3푠2[3/2] −2푠 2푝 3푝2[1/2]

NeI594.483푛푚, 2푠 2푝 3푠2[3/2] −2푠 2푝 3푝2[3/2]

Rates of excitation and radiative decay

Results Continue…

Single charged ions

Neutral atoms

ion lineNe II 333.484Ne II 356.585Ne II 371.313Ne I 585.258Ne I 588.189Ne I 594.483

Excita. Rate ne ne*Excita. Aki 10*Aki2.726E-07 1.301E+15 3.5E+08 1.80E+08 1.80E+092.972E-07 1.434E+15 4.3E+08 6.20E+07 6.20E+083.688E-07 3.713E+15 1.4E+09 1.30E+08 1.30E+092.650E-08 2.856E+16 7.6E+08 6.82E+07 6.82E+088.273E-09 5.412E+16 4.5E+08 1.15E+07 1.15E+081.440E-08 6.495E+16 9.4E+08 1.13E+07 1.13E+08

The plasma electron density ne each of these lines has been evaluated from a Voigt’s FWHM fit of the experimental profile

Partial local thermodynamics equilibrium found to be realized

Results Continue…

Results of investigation for excitation and radiative decay rates

10 times Radiative

decay

Excitation rate coefficient Excitation rate

Measured and simulated UV/VIS emission spectra of N2 photoionized plasma

LIFBASE: *J. Luque and D.R. Crosley. Lifbase: Database and spectral simulationprogram (version 2.1.1). SRI International Report MP 99-009, 1999.Specair: E. Pawelec, Eur. Phys. J. Special Topics 144, 227-231 (2007)

Results Continue…

positiveFirst :

positive Second :

negativeFirst :

332

332

222

ug

gu

gu

ABN

BCN

XBN

0.09.0x1031.8x1042.7x104

0.0

2.0x10-5

4.0x10-5

04080

300 325 350 375 400 425 450 475 5000

4080

N+2 (B-X)

1st negative

N2 (C-B)

Expt.

Tv = 2000 K

Inte

nsity

(arb

. uni

ts)

Specair

Non-thermal simulation Tv=2000 K, Tr = 320 K

LIFBASE

Non-thermal simulation Tv=3358.9 K, Tr = 320 K

2nd positive

Wavelength (nm)

LIFBASE

Vibrational levels

Emission lines originated from

the following band systems

The measured spectra dominated by vibrational transition in second positive and first negative systems of the nitrogen molecule

351 352 353 354 355 356 357 358

Experiment

Inte

nsity

(arb

. uni

ts)

Wavelength (nm)

Simulated: Specair @ Tv = 2000 K

N2(C3ug)

Results Continue…

Direct fitting of vibration bands give accurate data on theelectron vibrational temperature

And also result in a good agreement with the measuredvibrational levels

푵ퟐ(푪ퟑ횷풖 − 푩ퟑ횷품)

0 1 2 3 4 5 6

0.0

0.2

0.4

0.6

0.8

Tv = 2000, Tr = 320 Tv = 3358.9, Tr = 320

Vibr

atio

nal p

opul

atio

ns %

Vibrational levels11.16 11.28 11.40 11.52 11.64-6.0

-5.6

-5.2

-4.8

-4.4

-4.0

-3.6

ln(I v

',v'' v

',v''/

Av'

,v'')

Gv'(eV)

Tv = 3358.9 665 K

Vibrational populations of non-thermal modevibrational levels of 푁 , obtained at the end ofthe simulations for two different temperatures(Tv,Tr).

Vibrational temperature determination from the Boltzmann plot of the Δv= 0, ±1,-2, and -3 sequences in second positive band transitions푵ퟐ(푪ퟑ횷풖 −푩ퟑ횷품).

푙푛퐼(v , v ) × λ(v , v′′)

퐴(푣 ,푣′′)ℎ푣= −

ℎ푣퐺 푣퐾 푇

+ 퐶표푛푠푡.∗퐼 푣′,푣′′ intensity of vibrational bandG 푣′ vibrational energy of the upper level퐴 푣′, 푣′′ the transition probability and휆 푣′, 푣′′ is wavelength of the band head.

Results Continue…

Determination of vibrational푇 temperature of a plasma created in a molecular nitrogen

*C.O. Laux, Radiation and Nonequilibrium Collisional-Radiative Models, von Karman Institute Lecture Series, July 2002.

푵ퟐ(푪ퟑ횷풖 − 푩ퟑ횷품)

Summary and Outlook

LLP EUV sources were used to study time-integrated emission lines from photoionized plasmas in atomic and molecular gases.

The observed and identified spectral lines were mostly originated from radiative transitions in single and double charged ions.

Initial calculations of electron impact excitation and radiative decay rates were presented from neutral and singly charged ions.

We measured the band spectra (first negative and second positive systems) of the nitrogen molecule and we examined the vibrational temperature of the 푵ퟐ(푪ퟑ횷풖 −푩ퟑ횷품) band transitions.

Collision frequencies between the plasma particles and other plasma parameters will be evaluated for hydrodynamics calculations of the LPP EUV source in the near future.

[1] I.Saber, A. Bartnik, P. Wachulak, W. Skrzeczanowski, R. Jarocki and H. Fiedorowicz: Temporal variations of electrondensity and temperature in Kr/Ne/H2 photoionized plasma induced by nanosecond pulses from extreme ultraviolet(EUV) source, Physics of Plasmas 24, 063501 (2017); doi: http://dx.doi.org/10.1063/1.4984254[2] A. Bartnik, W. Skrzeczanowski, P. Wachulak, I. Saber, H. Fiedorowicz, T, Fok and Ł. Wegrzynski: Low-temperaturephotoionized plasmas induced in Xe gas using an EUV source driven by nanosecond laser pulses.Laser and Particle Beams 35(1), 42-47 (2017). DOI: https://doi.org/10.1017/S0263034616000781[3] I. Saber, A. Bartnik, P. Wachulak, W. Skrzeczanowski, R. Jarocki, and H. Fiedorowicz: Spectroscopic studies on time-integrated emission spectra in low- temperature neon photoionized plasma, ready to submit[4] I. Saber, A. Bartnik, W. Skrzeczanowski, P. Wachulak, R. Jarocki and H. Fiedorowicz: Emission spectra of photoionizedplasmas induced by intense EUV pulses: Experimental and theoretical investigations:AIP Conf. Proc. 1811, 140001 (2017). http://aip.scitation.org/doi/abs/10.1063/1.4975738[5] I. Saber, A. Bartnik, P. Wachulak, W. Skrzeczanowski, R. Jarocki and H. Fiedorowicz: Spectral lines and characteristic oftemporal variations in photoionized plasmas induced with laser-produced plasma extreme ultraviolet source.Proc. Nucl. Inst.methods research B (NIMB). https://doi.org/10.1016/j.nimb.2017.06.017[6] I. Saber, A. Bartnik, P. Wachulak,W. Skrzeczanowski, R. Jarocki, H. Fiedorowicz: Photoionization of atomic neoninduced using nanosecond pulses of extreme ultraviolet source.Proc. of the 15th International Conference on X-ray Lasers (ICXRL 2016) in Japan.[7] A.Bartnik, W.Skrzeczanowski,P.Wachulak, I.Saber, H.Fiedorowicz, T.Fok, Ł.Węgrzyński: Reflective optics for effectivecollection of x-ray and EUV radiation: use for creation of photoionized plasmas and detection of weak signals.Vol.102350D (2017); http://doi: 10.1117/12.2269438[8] I. Saber, A. Bartnik, P. Wachulak, W. Skrzeczanowski, R. Jarocki, H. Fiedorowicz and J. Limpouch: Experimental andtheoretical emission spectra in nitrogen photoionized plasma induced with intense EUV pulses,Proc. of European Physical Journal (EPJ). To be submitted.

Publications & Conf. Proceedings

The research was supported by the EMJD ProgrammeEXTATIC (No 2012-0033), the National Science Centre; award numbers MO2015/17B/ST7/03718, UMO-2015/19/B/ST3/0043 and by the Laserlab Europe project (EU-H2020 654148).

Acknowledgements:

Dr. A. Bartnik MUTProf. J. Limpouch CTUProf. H. Fiedorowicz MUTDr. P. Wachulak MUT

Thank you for your attention

Approximate estimation of ne

푙푒 =1푛σ

Main free path of photoelectrons 흈= 흈풊+ 흈ex

Assume that thermalization is possible in case 푙<<d Where d is plasma size and assumed to be 1 mm

10 -17 cm2

풏 ̴ 2.25 x 1017 cm-3

The lower limit for electron density for which plasma, somehow to satisfy LTE*

32/1123 1061018.1 ETcmn ee

*R. W. P. McWhirter, Spectral Intensities, in Plasma Diagnostic Techniques, ed. R. H. Huddlestone and S. L. Leonard, Academic Press, New York, 1965, ch. 5, p. 206.

∆E is the higher energy different in eV of the levels whose populations are given by LTE conditions

Electron density has been determined from the line profiles of the isolated Kryptonneutral lines neglecting the contribution of the ion impact broadening and Dopplerbroadening

Δλ = 0.00884 nm, Lorentzian FWHM휔 =0.0886 nm, Stark broadening parameterNr (reference electron density).Neutral atoms: Nr =1016 cm-3

Singly ionized atoms: Nr =1017cm-3

31416

1050886.02

1000884.0

cmNe

N. Konjevic et al, J. of Phys. Chem. Ref. Data 31, 819 (2002).

*J. Luque and D.R. Crosley. Lifbase: Database and spectralsimulation program (version 2.1.1). SRI International Report MP 99-009, 1999.

AbstractEmission lines in different electromagnetic radiations from lowtemperature photoionized plasmas of atomic and molecular gaseswere investigated. The photoionized plasmas were induced usingnanosecond radiation pulses of laser-produced plasma extremeultraviolet (EUV) source. The source was based on a doublestream gas puff target irradiated with a commercial Nd:YAG laserof 10 ns 10 Hz repetition rate with low and high pulse energysystem. The EUV radiations were focused onto a gas stream,injected into a vacuum chamber synchronously with the EUVpulses. The radiation was collected and focused using differentEUV collectors. A range of non-local equilibrium (NLTE) modelsand the radiative collisional codes have been used to reproducedtheoretical spectra for further interpretation.