A Dynamic Mass Spectrometer for the Study of Laser-Produced Plasmas

Oron, M.; Paiss, Y.

doi:10.1063/1.1686373

Cited by 22 publications

(3 citation statements)

References 5 publications

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“…A single-shot electrodynamic charge analyzer (Oron & Pais 1973;Chowdhury et al 1980) was constructed and used to separate the incoming multicharge state ion beam into individual charge states. Figure 7 shows a schematic diagram of the charge analyzer.…”

Section: Charge State Measurements Of a Krf Laser-produced Expanding mentioning

confidence: 99%

KrF laser-plasma interaction experiments with ns and ps pulses

et al. 1992

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We report on KrF laser-plasma interaction studies at focused intensities up to 4 x 10 14 W/cm 2 for pulse durations of 1-2 ns and up to 10 15 W/cm 2 for pulse duration of 100 ps. The longer-pulse experiments are concerned with quantifying two important features of the ablating plasma. Stimulated Brillouin scattering at moderately large L/X has been measured in detail as a function of intensity, target Z, and angle of incidence 0 to compare with modeling calculations of backscatter in inhomogeneous plasma. In addition, electrodynamic charge analyzer measurements have been made for varying intensity and target Z to compare with hydrodynamic calculations of ion expansion and recombination. In the shortpulse experiments, we report on X-ray conversion measurements for 100-ps laser-irradiated targets of varying Z at laser intensities of 1.5 X 10 14 and 10 15 W/cm 2 . In particular, it is shown that higher laser intensity leads to a substantial increase in X-ray conversion efficiency.

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Section: Charge State Measurements Of a Krf Laser-produced Expanding mentioning

confidence: 99%

KrF laser-plasma interaction experiments with ns and ps pulses

et al. 1992

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“…The ions are analysed in a time-of-flight tube followed by the dynamic, capacitor-like analyser. This combination enables one to determine simultaneously the relative yield and energy distribution of all the ions created in one laser shot [10], Typically, in the case of oxygen-doped LiD spherical targets, we examine L + , L ++ , L +++ , D + , and O* 4 through O +7 . A sample of the data obtained is shown in Fig.…”

Section: Diagnosticsmentioning

confidence: 99%

Short-pulse-laser-heated plasma experiments

Soures¹,

Goldman²,

Lubin³

1973

Nucl. Fusion

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The interaction between time-tailored, high-intensity laser radiation and spherical light-element targets is investigated. Simultaneous measurements of the laser plasma electron temperature, charged-particle distribution, absorbed energy, neutron yields and backscattered light intensity and spectra were made. For 100 ps, wide laser pulses focused to intensities ranging between 3 × 1015 and 2 × 1016 W/cm2 on 150-200μm-diameter LiD and C36D74 targets, plasmas with electron temperatures up to 1.2 keV and target-generated yields of up to 4 × 104 neutrons are produced. The absorption can be accounted for by inverse bremsstrahlung and no.significant contributions due to parametric instabilities are observed. No more than 10−1 of the incident laser energy is back-reflected into spectral components at ωL, (3/2,)ωL, and 2ωL.

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“…Even though these devices can access the plasma ion velocity distribution directly and have been proved successful in a number of plasma machines, there are generally two major drawbacks. The energy analyzers either use a constant electric field such as retarding field systems [15] and deflection systems [16] or pulsed electric field [17] to separate ions with different energies, which will perturb the local plasma potential. Moreover, the devices have to be immersed in the plasma to make measurements and this will introduce potential contaminates to the plasma.…”

Section: -Winston Churchillmentioning

confidence: 99%

Validation of a Lagrangian model for laser-induced fluorescence

Chu¹

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To my parentsii v Since man is not born with knowledge, who can be without doubts? If one has doubts and is not willing to learn from a teacher, his doubts will never be resolved. Those who were born before me must have learned the Tao earlier than me, and I take them as my teachers. Those who were born after me may also have learned the Tao earlier than me, and I take them as my teachers. Since the Tao is what I desire to learn, why should I care if my teachers were born before or after me? Therefore, whether a man is noble or lowly, old or young, where there is the Tao, there is my teacher.vi ABSTRACT Extensive information can be obtained on wave-particle interactions and wave fields by direct measurement of perturbed ion distribution functions using laserinduced fluorescence (LIF). For practical purposes, LIF is frequently performed on metastable states that are produced from neutral gas particles and ions in other electronic states. If the laser intensity is increased to obtain a better LIF signal, then optical pumping can produce systematic effects depending on the collision rates which control metastable population and lifetime. We numerically simulate the ion velocity distribution measurement and wave-detection process using a Lagrangian model for the LIF signal. The simulations show that optical pumping broadening affects the ion velocity distribution function (IVDF) f 0 (v) and its first-order perturbation f 1 (v, t) when laser intensity is increased above a certain level. The results also suggest that ion temperature measurements are only accurate when the metastable ions can live longer than the ion-ion collision mean free time. For the purposes of wave detection, the wave period has to be significantly shorter than the lifetime of metastable ions for a direct interpretation. Experiments are carried out to study the optical pumping broadening and metastable lifetime effects, and the results are compared with the simulation in order to validate the Lagrangian model for LIF. It is more generally true that metastable ions may be viewed as test-particles. As long as an appropriate model is available, LIF can be extended to a range of environments. vii PUBLIC ABSTRACTIn laser-induced fluorescence (LIF), measurements of spontaneous light emission after laser excitation of plasma particles provides useful insight into some its qualities, like its ion temperature and wave-particle interaction dynamics.Usually physicists analyze LIF results with the fixed coordinate-based Eulerian approach. But in this thesis, we apply a Lagrangian approach to LIF analysis using newly written code to follow each individual ion orbit. We found the Lagrangian model, with which we numerically simulated the ion velocity and wave-detection process, is more efficient and revealing than the Eulerian approach. It computationally allows a separation of the quantized description of ionic states from the classical dynamics of the ion center of mass. Also, some key calculations can be done by hand and included readily, leading to large tim...

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A Dynamic Mass Spectrometer for the Study of Laser-Produced Plasmas

Cited by 22 publications

References 5 publications

KrF laser-plasma interaction experiments with ns and ps pulses

KrF laser-plasma interaction experiments with ns and ps pulses

Short-pulse-laser-heated plasma experiments

Validation of a Lagrangian model for laser-induced fluorescence

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