B. Busch

Emission of vacuum ultraviolet radiation from neon excimers excited by a heavy ion beam

The vacuum ultraviolet emission of neon excited with a pulsed 100 MeV 32S9+ ion beam from the Munich Tandem van de Graaff accelerator was studied at pressures between 1.8 and 96.1 kPa. In the wavelength range between 70 and 110 nm the first, second, and third excimer continua were observed. From time‐ and pressure‐dependent studies of the third continuum emission at a wavelength of 99 nm, rate coefficients k2=(3.6±0.3)×10−13 cm3/s for the bimolecular reaction Ne2++Ne→2Ne+ and k3=(2.84±0.09)×10−31 cm6/s for the termolecular reaction Ne2++2Ne→(Ne2+Ne)2++Ne were determined.

Heavy ion excitation of solid rare gases

The vacuum ultraviolet (VUV) emission of solid Ar, Kr, and Xe targets excited by heavy ion beams was studied in order to explore the possibility of VUV laser action. A pulsed 75 MeV 32S beam with 14.4 μJ pulse energy and 2 ns pulse width was used. Wavelength spectra measured during 10 and 90 ns time windows after the beam pulse showed strong VUV emission from the decay of the quasi‐molecular 1Σ+u and 3Σ+u self‐trapped excitons. The decay times of these states were measured for all three rare‐gas targets. Cross sections for stimulated emission of 5.7×10−18, 1.3×10−17, and 2.4×10−17 cm2 in Ar, Kr, and Xe, respectively, were deduced from the linewidth and lifetime of the 1Σ+u to ground‐state transition. A 1Σ+u state population density of 9.6×1013 cm−3 was determined in solid Xe from an absolute intensity measurement.

Third excimer continua in neon and argon

The emission of the third continuum of argon in the wavelength range between 175 and 250 nm and the vacuum ultraviolet emission of neon (λ 32 S 9+ ions from the Munich Tandem van de Graaf accelerator. Wavelength spectra recorded in different time windows after the 2-ns beam pulses show that two different components contribute to the third continuum of argon. A radiative lifetime of 5.71 ± 0.08 ns for the Ar 2 2+ molecule and a rate coefficient k 3 = (1.46 ± 0.12) x 10 -30 cm 6 /s for the reaction Ar 2+ + 2Ar → Ar 2 2+ + Ar were obtained from the pressure dependence of time spectra at a wavelength of 190 nm. From time- and pressure-dependent studies of the third continuum emission of neon at a wavelength of 99 nm, rate coefficients k 2 = (3.6 ± 0.3) x 10 -13 cm 3 /s for the bimolecular reaction Ne 2+ + Ne→ 2Ne + and k 3 = (2.84 ± 0.09) X 10 -31 cm 6 /s for the termolecular reaction Ne 2+ + 2Ne → Ne 2 2+ + Ne were determined.

Optical gain on the 476.5 nm Argon-ion laser line in a gas-target excited by a heavy ion beam

Optical gain on the 476.5 nm Ar II 4p−4s ion laser transition has been observed in argon-gas excited by 2.5 ns pulses of 90 MeV32S ions with a repetition rate of 4883 Hz. The energy per pulse was 23 μJ. The projectiles were stopped in the target at pressures between 5 and 20 kPa. Gain was determined from a measured transient increase of the intensity of a 476.5 nm probe laser beam sent along the ion beam axis and back reflected by an aluminum foil. The maximum gain observed was (0.4±0.1)×10−3 at a target-gas pressure of 5 kPa. Control experiments using krypton as target-gas were performed and yielded a null result. The optical gain observed in argon is consistent with the result from an analysis of spectroscopic studies of rare-gas targets excited by heavy ion beams.

Emission of light from matter excited by heavy-ion beams☆

Abstract The emission of light from rare-gas targets excited by a pulsed 100 MeV 32 S 8+ beam is studied by time-resolved optical spectroscopy. A waveleng

Heavy ion beam excitation of rare gases

The emission of light from rare gas targets at pressures of more than 100 Pa excited by a pulsed heavy ion beam has been studied. The absolute intensity of several spectral lines has been measured as a function of time at different target gas pressures. Population densities, excitation cross sections, and rate constants for collisional quenching were determined from the line intensities and the lifetimes of the excited states.

PROSPECTS FOR PARTICLE BEAM PUMPED SHORT WAVELENGTH LASERS

Publisher Summary The chapter focuses on heavy ion beam pumping, which provides a potentially significant laser excitation technique for producing short wavelength high power lasers. Heavy ion accelerators, providing ions from several MeV to several GeV, have primarily been used for single collision nuclear and atomic physics experiments. Instantaneous electric fields in ion–atom collisions can be several hundred e/a o 2 with correspondingly high time derivatives. This leads to large multiple ionization cross sections with relatively cool recoil ions moving transverse to the beam. During the rise time, specific target and beam combinations could lead to population inversion situations. During the peak of the pulse, a dense target will radiate strongly in the soft x-ray range of the spectrum—possibly of use for optical pumping. Recombination lasers are possible during the cooling of the target plasma. An additional enhancement of the power density can occur in a specially designed target by an implosion in the hydrodynamic phase. Detailed calculations using codes that have been developed for laser produced plasmas must be modified for the heavy ion beam case.