The experimental and theoretical investigations of damage development and distribution in double-forged tungsten under plasma irradiation-initiated extreme heat loads

Abstract

Abstract. The infl uence of extreme heat loads, as produced by a multiple pulses of non-homogeneous fl ow of slow plasma (0.1-1 keV) and fast ions (100 keV), on double-forged tungsten (DFW) was investigated. For generation of deuterium plasma and fast deuterons, plasma-focus devices PF-12 and PF-1000 are used. Depending on devices and conditions, the power fl ux density of plasma varied in a range of 10 7 -10 10 W/cm 2 with pulse duration of 50-100 ns. Power fl ux density of fast ions was 10 10 -10 12 W/cm 2 at the pulse duration of 10-50 ns. To achieve the combined effect of different kind of plasmas, the samples were later irradiated with hydrogen plasma (10 5 W/cm 2 , 0.25 ms) by a QSPA Kh-50 plasma generator. Surface modifi cation was analysed by scanning electron microscopy (SEM) and microroughness measurements. For estimation of damages in the bulk of material, an electrical conductivity method was used. Investigations showed that irradiation of DFW with multiple plasma pulses generated a mesh of micro-and macrocracks due to high heat load. A comparison with single forged tungsten (W) and tungsten doped with 1% lanthanum-oxide (WL10) reveals the better crack-resistance of DFW. Also, sizes of cells formed between the cracks on the DFW's surface were larger than in cases of W or WL10. Measurements of electrical conductivity indicated a layer of decreased conductivity, which reached up to 500 m. It depended mainly on values of power fl ux density of fast ions, but not on the number of pulses. Thus, it may be concluded that bulk defects (weakening bonds between grains and crystals, dislocations, point-defects) were generated due to mechanical shock wave, which was generated by the fast ions fl ux. Damages and erosion of materials under different combined radiation conditions have also been discussed.

The INVESTIGATION OF RADIATION EFFECT ON TUNGSTEN AND MOLYBDENUM MATERIALS

“…Thus, the surface damage is proportional rise of surface temperature. Solving the 1D heat equation for homogeneous finite-duration heat loads on semi-infinite surfaces enables to calculation of the maximal rise of the material's surface temperature [28]. The sample surface temperature was calculated as follows:…”

Investigation of Anisotropy of Neutron Emission in the Thermonuclear Plasma Focus Installation

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“…Соңғы жылдары плазмалық фокус қондырғысында дейтерий газын қолдану кезінде плазманың қалыптасу динамикасы мен оның 10 −9 -10 −6 секунд аралығындағы сығылуына (пинчтелу) қатысты теориялық [2] және эксперименттік [1][2][3][4][5][6][7][8] зерттеу жұмыстары елеулі дәрежеде дамыды. Алайда, қазіргі таңда көптеген зерттеу жобаларының назарын, плазмалық фокус қондырғысындағы интенсивті рентген сәулелері мен жылдам нейтрондардың пайда болу механизмі өзіне тартып келеді.…”

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