MeV bremsstrahlung X rays from intense laser interaction with solid foils. (24th January 2019)

• Record Type: Journal Article
• Authors: Palaniyappan, S.; Gautier, D. C.; Tobias, B. J.; Fernandez, J. C.; Mendez, J.; Burris-Mog, T.; Huang, C. K.; Favalli, A.; Hunter, J. F.; Espy, M. E.; Schmidt, D. W.; Nelson, R. O.; Sefkow, A.; Shimada, T.; Johnson, R. P.
• Is Part Of: Laser and particle beams. Volume 36:Number 4(2018)
• Page Start: 502
• Page End: 506
• Publication Date: 2019-01-24
• Subjects: Intense laser–plasma, -- MeV X-ray radiography; Laser beams -- Periodicals; Particle beams -- Periodicals; 535.5
• DOI: 10.1017/S0263034618000551
• Languages: English
• ISSNs: 0263-0346

Abstract

Abstract: Laser-based compact MeV X-ray sources are useful for a variety of applications such as radiography and active interrogation of nuclear materials. MeV X rays are typically generated by impinging the intense laser onto ~mm-thick high-Z foil. Here, we have characterized such a MeV X-ray source from 120 TW (80 J, 650 fs) laser interaction with a 1 mm-thick tantalum foil. Our measurements show X-ray temperature of 2.5 MeV, flux of 3 × 10 12 photons/sr/shot, beam divergence of ~0.1 sr, conversion efficiency of ~1%, that is, ~1 J of MeV X rays out of 80 J incident laser, and source size of 80 m. Our measurement also shows that MeV X-ray yield and temperature is largely insensitive to nanosecond laser contrasts up to 10 −5 . Also, preliminary measurements of similar MeV X-ray source using a double-foil scheme, where the laser-driven hot electrons from a thin foil undergoing relativistic transparency impinging onto a second high-Z converter foil separated by 50–400 m, show MeV X-ray yield more than an order of magnitude lower compared with the single-foil results.