عنوان

A Mass Spectrometry Study of Isotope Separation in the Laser Plume

شماره

TL7b34v9f8

زبان متن نوشتاري يا گفتاري و مانند آن

انگلیسی

عنوان اصلي

A Mass Spectrometry Study of Isotope Separation in the Laser Plume

نام عام مواد

[Thesis]

نام نخستين پديدآور

Suen, Timothy Wu

نام ساير پديدآوران

Mao, Samuel S; Greif, Ralph

نام ناشر، پخش کننده و غيره

UC Berkeley

تاریخ نشرو بخش و غیره

2012

کسي که مدرک را اعطا کرده

UC Berkeley

امتياز متن

2012

متن يادداشت

Accurate quantification of isotope ratios is critical for both preventing the development of illicit weapons programs in nuclear safeguards and identifying the source of smuggled material in nuclear forensics. While isotope analysis has traditionally been performed by mass spectrometry, the need for in situ measurements has prompted the development of optical techniques, such as laser-induced breakdown spectroscopy (LIBS) and laser ablation molecular isotopic spectrometry (LAMIS). These optical measurements rely on laser ablation for direct solid sampling, but several past studies have suggested that the distribution of isotopes in the ablation plume is not uniform.This study seeks to characterize isotope separation in the laser plume through the use of orthogonal-acceleration time-of-flight mass spectrometry. A silver foil was ablated with a Nd:YAG at 355 nm at an energy of 50 μJ with a spot size of 71 μm, for a fluence of 1.3 J/cm² and an irradiance of 250 MW/cm². Flat-plate repellers were used to sample the plume, and a temporal profile of the ions was obtained by varying the time delay on the high-voltage pulse. A spatial profile along the axis of the plume was generated by changing the position of the sample, which yielded snapshots of the isotopic composition with time. In addition, the reflectron time-of-flight system was used as an energy filter in conjunction with the repellers to sample slices of the laser plasma orthogonal to the plume axis.Mass spectrometry of the plume revealed a fast ion distribution and a slow ion distribution. Measurements taken across the entire plume showed the fast ¹⁰⁹Ag ions slightly ahead in both space and time, causing the ¹⁰⁷Ag fraction to drop to 0.34 at 3 μs, 4 mm from the sample surface. Although measurements centered on the near side of the plume did not show isotope separation, the slow ions on the far side of the plume included much more ¹⁰⁹Ag than ¹⁰⁷Ag. In addition to examining the isotope content of the ablation plume, this study has developed a mass spectrometry characterization technique that may be useful for investigating chemical reactions during laser ablation.

مستند نام اشخاص تاييد نشده

Suen, Timothy Wu

مستند نام اشخاص تاييد نشده

Mao, Samuel S; Greif, Ralph

مستند نام تنالگان تاييد نشده

UC Berkeley

نام الکترونيکي

فرمت انتشار

p

نوع ماده

[Thesis]

کد کاربرگه

276903

سطح دسترسي

a

تكميل شده

Y