Generation of gamma radiation by a subterawatt ultrashort laser pulse: optimisation of preplasma and pulse duration

Journal Article · Wed Apr 01 00:00:00 EDT 2020 · Quantum Electronics (Woodbury, N.Y.)

DOI:https://doi.org/10.1070/QEL17263· OSTI ID:23141918

Shulyapov, S. A.; Ivanov, K. A.; Gospodinov, G. A.; Volkov, R. V.; Savel’ev, A. B. ^[1]; Tsymbalov, I. N. ^[2]

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1. Faculty of Physics, Lomonosov Moscow State University, Vorob’evy gory, 119991 Moscow (Russian Federation)
2. International Laser Centre, Lomonosov Moscow State University, Vorob’evy gory, 119991 Moscow (Russian Federation)

We report an experimental and numerical study of the acceleration of electrons in a plasma interacting with a subterawatt laser pulse (intensity of ∼3 × 10{sup 18} W cm{sup −2} at a pulse duration of 50 fs). A preplasma layer on the surface of a molybdenum target is formed by an additional laser pulse with a duration of 8 ns and an intensity of ∼2 × 10{sup 12} W cm{sup −2}. It is shown that an increase in the laser pulse duration to 1700 fs at a constant energy (and a proportional decrease in intensity) leads to an increase in the yield of bremsstrahlung γ-radiation by more than an order of magnitude when the nanosecond pulse is ahead of the femtosecond one by 15 − 25 ns. Interferometry data and results of diagnostics of optical and γ-radiation of a plasma demonstrate that the collisional ionisation of atoms by electrons oscillating in the field of such a laser pulse plays an essential role in the formation of electron density profile. The sensitivity of the described effect to the level of amplified spontaneous emission is determined, despite the nanosecond pulse impact. Numerical simulations show that at a large pulse duration, the acceleration of electrons is stipulated by the beaking of plasma waves excited during stimulated Raman scattering of laser radiation. (paper)

• OSTI ID: 23141918
• Journal Information: Quantum Electronics (Woodbury, N.Y.), Vol. 50, Issue 4; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 1063-7818
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
70 PLASMA PHYSICS AND FUSION TECHNOLOGY
ACCELERATION
COMPUTERIZED SIMULATION
ELECTRON DENSITY
ELECTRONS
GAMMA RADIATION
INTERFEROMETRY
IONIZATION
LASER RADIATION
LASERS
LAYERS
NUMERICAL ANALYSIS
OPTIMIZATION
PLASMA WAVES
PULSES
RAMAN EFFECT
SENSITIVITY
SURFACES