Thin tape target driver for laser ion accelerator

Nayuki, Takuya; Oishi, Yuji; Fujii, Takashi; Nemoto, Koshichi; Kayoiji, Tsutomu; Okano, Yasuaki; Hironaka, Yoichiro; Nakamura, Kazutaka G.; Kondo, Ken‐ichi; Ueda, Ken–ichi

doi:10.1063/1.1578156

Cited by 58 publications

(31 citation statements)

References 7 publications

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“…To resolve target life-time issues, fast target replacement schemes have been introduced by some groups 8,15,[17][18][19] . In particular, using ∼ 100 mJ of pulse energy at 10 Hz repetition-rate, Ditmire et.…”

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confidence: 99%

High repetition-rate neutron generation by several-mJ, 35 fs pulses interacting with free-flowing D2O

Hah

Petrov

Nees

et al. 2016

Applied Physics Letters

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Using several-mJ energy pulses from a high-repetition rate ( 1 ⁄2 kHz), ultrashort (35 fs) pulsed laser interacting with a ∼ 10 µm diameter stream of free-flowing heavy water (D 2 O), we demonstrate a 2.45 MeV neutron flux of 10 5 /s. Operating at high intensity (of order 10 19 Wcm −2 ), laser pulse energy is efficiently absorbed in the pre-plasma, generating energetic deuterons. These collide with deuterium nuclei in both the bulk target and the large volume of low density D 2 O vapor surrounding the target to generate neutrons through d (d, n) 3 He reactions. The neutron flux, as measured by a calibrated neutron bubble detector, increased as the laser pulse energy was increased from 6 mJ to 12 mJ. A quantitative comparison between the measured flux and results derived from 2D particle-in-cell simulations show comparable neutron fluxes for similar laser characteristics to the experiment. The simulations reveal that there are two groups of deuterons; forward moving deuterons generate D−D fusion reactions in the D 2 O stream and act as a point source of neutrons, while backward moving deuterons propagate through the low-density D 2 O vapor filled chamber and yield a volumetric source of neutrons.Energetic neutrons have numerous applications in many fields, including medicine 1 , homeland security 2 , and material science 3 . Conventional fast neutron sources include deuterium−deuterium (D−D) and deuteriumtritium (D−T) fusion generators, as well as light-ion, photoneutron and spallation sources. Laser plasma interactions in the relativistic regime can also generate charged particles and subsequently accelerate them to energies high enough to trigger nuclear fusion reactions, resulting in neutron production [4][5][6][7][8][9][10][11][12][13][14][15][16] . Recent advances in ultra-high power laser technology now enable tabletop scale systems, which may be further reduced in size for use as drivers for portable neutron generators in the future. One of the methods for neutron production is through the acceleration of high-energy ions (keV-MeV) impinging upon an appropriate converter target, such as deuterated plastic. Typically, thin solid targets are used in these experiments to accelerate deuterons.Using solid targets in the form of a thin (1µm) foil has some drawbacks for high repetition-rate (>kHz) operation; for example, one has to replace the target after each shot. To resolve target life-time issues, fast target replacement schemes have been introduced by some groups 8,15,[17][18][19] . In particular, using ∼ 100 mJ of pulse energy at 10 Hz repetition-rate, Ditmire et. al. 8 used deuterium clusters, which were rapidly heated by the laser pulse (on a femtosecond time scale) and launched few a) Now at Physics Department, Lancaster University, UK keV deuterons to drive D−D fusion reactions.In this Letter, we report the production of neutrons using a high repetition-rate ( 1 ⁄2 kHz) femtosecond laser at high intensities (> 10 19 Wcm −2 for vacuum focus) but low pulse energies (several-mJ) interacting with a heavy...

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confidence: 99%

High repetition-rate neutron generation by several-mJ, 35 fs pulses interacting with free-flowing D2O

Hah

Petrov

Nees

et al. 2016

Applied Physics Letters

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“…Thus, we need to evaluate the ‰uctua-tion in the tape target position. Nayuki et al measured the change in the position of the tape target by using a laser displacement meter without using a high-intensity laser beam 12) . To date, the reproducibility of the target surface position of such a tape target has not been observed under actual target irradiation conditions.…”

Section: Introductionmentioning

confidence: 99%

“…A target must therefore be supplied at the same rate as that of the laser pulses. The tape target technique [12][13] is one of the methods for continuously supplying the target material. In this method, displacements in the surface position of the target cause unwanted ‰uctuations in the energy and number of emitted protons at each laser shot.…”

Section: Introductionmentioning

confidence: 99%

“…In this method, displacements in the surface position of the target cause unwanted ‰uctuations in the energy and number of emitted protons at each laser shot. To maintain precision of the surface position, the tape target must be tensioned 12) . At too low tensions, the surface position is displaced because of motor vibrations 12) or wrinkles formed in the tape at the time of production.…”

Section: Introductionmentioning

confidence: 99%

“…To maintain precision of the surface position, the tape target must be tensioned 12) . At too low tensions, the surface position is displaced because of motor vibrations 12) or wrinkles formed in the tape at the time of production. When a tumor at a depth of ¿15 cm is to be irradiated with an accuracy of 5 mm, it is necessary to irradiate the proton with an energy accuracy of 0.25 MeV.…”

Section: Introductionmentioning

confidence: 99%

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A Novel Technique for Monitoring the Reproducibility of Laser Tape-Target Interactions Using an X-ray Pinhole Camera

Fukumi¹,

Zhong²,

Orimo

et al. 2009

J. Vac. Soc. Jpn.

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For accurately controlling relativistic laser-plasma interactions to achieve repetitive proton generation, it is necessary to measure and control the laser irradiation conditions, such as laser parameters and target shooting accuracy, as well as to measure proton parameters for each laser shot. The displacement of the tape target, which is used in an ultra-short Ti: sapphire laser system to generate high-energy protons, is measured by capturing X-ray images of the laser plasma for each laser shot using an X-ray pinhole camera. This method allows the displacement of the target to be measured with a precision of 10 mm. The precision is high enough for present-day laser focusing systems with an F-number of 3.6 ( f＝179 mm). Thus, the proposed technique contributes to accurate control of repetitive laser-driven proton generation.

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MeV‐class electron generation with compact generator using ultra short pulse laser

Takano

Nayuki

Oishi

et al. 2008

Elect Comm in Japan

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SUMMARYA compact laser electron source usable instead of radioisotopes as an X-ray source for nondestructive diagnosis was developed. High-energy electrons were generated by an ultrashort pulse focused on a thin tape target. The laser energy was only 15 mJ. The pulse duration and beam diameter of the laser beam were 140 fs and 10 mm, respectively. Electron energies above 1 MeV were obtained with this compact laser electron source.

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Thin tape target driver for laser ion accelerator

Cited by 58 publications

References 7 publications

High repetition-rate neutron generation by several-mJ, 35 fs pulses interacting with free-flowing D2O

High repetition-rate neutron generation by several-mJ, 35 fs pulses interacting with free-flowing D2O

A Novel Technique for Monitoring the Reproducibility of Laser Tape-Target Interactions Using an X-ray Pinhole Camera

MeV‐class electron generation with compact generator using ultra short pulse laser

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