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Spektrometria aktywacyjna dla potrzeb drugiej kampanii deuterowo-trytowej na Tokamaku JET

Łaszyńska E., Jednoróg S.

Postępy Techniki Jądrowej

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2016

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z. 4

21--29

PL

Metoda aktywacyjna stosowana do charakteryzacji różnych źródeł neutronów, należy do jednej z najstarszych metod stosowanych w neutronice. Pomimo tego jest wciąż ważna, gdyż prowadzi do otrzymywania wartości bezwzględnych wydajności neutronów, a czasami pozwala na dekonwolucje ich rozkładu energetycznego. Druga Deuterowo- Trytowa Kampania Eksperymentalna na Wspólnym Europejskim Tokamaku JET jest wielkim wyzwaniem. Po jej zakończeniu nastąpi zamknięcie i odstawienie JETa, a tym samym zakończenie jakże ważnego rozdziału w historii fizyki plazmy. Przed kampanią deuterowo-trytową nastąpi kalibracja diagnostyk neutronowych tokamaka i to z niepewnością niższą niż 5%. Technika aktywacyjna posłuży do charakteryzacji generatora neutronów, który będzie zastosowany, jako ustandaryzowane źródło neutronów 14 MeV, a następnie będzie zastosowana w czasie ostatniej kampanii eksperymentalnej do monitorowania wydajności neutronów.

EN

The activation technique used for characterization of many different neutron sources belongs to the oldest one applied in neutronics area. It is still important because it leads to obtainment of obsolete value of neutron yield and from time to time allows neutron spectrum deconvolution. The Second Deuterium-Tritium Experimental Campaign that is held on Joint European Torus is a great challenge. After completing the above campaign the shut down and decommissioning of the JET is expected. Thus, the important chapter in history of plasma physics will be definitely closed. But before the deuterium-tritium campaign starts, the calibration of neutron diagnostic should be completed with uncertainty better than 5%. The activation technique is used for neutron diagnostics characterization that is chosen as the source of 14 MeV neutrons. Afterwards, the activation technique will be applied as neutron yield monitor during last experimental campaign on JET tokamak.

2

Status of a mega-joule scale Plasma-Focus experiments

Scholz M., Bieńkowska B., Borowiecki M., Ivanova-Stanik I., Karpiński L., Stępniewski W., Paduch M., Tomaszewski K., Sadowski M., Szydłowski A., Kubeš P., Kravárik J.

Nukleonika

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2006

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Vol. 51, nr 1

79-84

EN

This paper presents results of the recent plasma-focus (PF) experiments carried out with PF facilities, which was operated at energies ranging from 0.5 MJ to about 1 MJ. Particular attention has been paid to pinch evolution, the emission of pulsed X-ray, fast electron beams, and fusion produced neutrons. Some theoretical models of the initial breakdown, which occurs at the insulator surface, are compared. It is pointed out that modeling of the breakdown is sensitive to kinetics of ionization processes and transport coefficients. Progress in experimental studies of the axial acceleration phase is unsatisfactory. Important experimental data have been collected, but new measurements are still needed. For the radial collapse phase, it was shown that the MHD modeling is efficient until the maximum compression, but plasma instabilities require more sophisticated approaches. The pinch phase was investigated by means of different diagnostics. Fusion neutron yields were measured in different experiments, but some discrepancies in scaling must still be explained. The conclusions concern directions for further studies and optimization of large-scale high-current PF facilities.

3

Results of large scale Plasma-Focus experiments and prospects for neutron yield optimization

Sadowski M., Scholz M.

Nukleonika

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2002

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Vol. 47, nr 1

31-37

EN

This paper summarizes results of the recent Plasma-Focus (PF) studies carried out with different PF facilities in Poland, which were operated at energies ranging from 100 kJ to about 1000 kJ. Particular attention has been paid to currentsheath (CS) dynamics, the emission of pulsed X-rays, fast electron beams, energetic ion beams, and fusion-produced neutrons. Some efforts, undertaken in order to increase the neutron emission, have been described. In particular, nuclear targets made of D2O-ice layers, which were deposited upon special cryogenic devices, have been applied in the PF-360 machine. An increase in the neutron yield from 2.4×1010 up to 3.8×1010 neutrons per shot has been achieved in 130-kJ discharges. With the PF-1000 machine, for the first time the well-formed plasma pinch columns were obtained in PF discharges performed at 1 MJ, and the neutron yield of 2×1011 neutrons per shot was achieved.

4

Studies of Plasma-Focus discharges within the PF-360 facility equipped with a planar D2O-ice target

Zebrowski J., Baranowski J., Jakubowski L., Sadowski M.

Nukleonika

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2001

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Vol. 46, suppl. 1

65--68

EN

The paper reports on investigations of dense magnetized plasmas produced within a modernized PF-360 facility, which was operated with an additional planar cryogenic target placed in the front of the electrode outlet and covered with D2O-ice layers. The main aim of these studies was to overcome the neutron saturation effect and to increase the maximum neutron yield from PF discharges by using fast deuteron beams. Such beams are usually emitted from a pinch region and can produce fast neutrons from D-D reactions during their interactions with the additional target.

5

Neutron and fast ion emission from PF-1000 facility equipped with new large electrodes

Szydlowski M., Scholz M., Karpinski L., Sadowski M., Tomaszewski K., Paduch M.

Nukleonika

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2001

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Vol. 46, suppl. 1

61--64

EN

A PF-1000 facility was operated for the first time at an energy level of up to 1 MJ. The maximal emission of 2×1011 neutrons/shot was registered. Relatively low emission anisotropy was observed. Fast ion beams were generated only from shots performed at a low filling pressure (1-2 Torr).

6

Investigation of Plasma Focus discharges in the PF-360 facility with additional D2 gaspuffed targets

Stanislawski J., Baranowski J., Sadowski M., Zebrowski J.

Nukleonika

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2001

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Vol. 46, suppl. 1

73--75

EN

The paper describes experimental studies of Plasma-Focus (PF) discharges carried out within the modernized PF- 360 facility, which was operated with an additional D2-gas puffing into the region of the collapsing current sheath and PF pinch formation, i.e. into space in front of the electrode outlet. The main aim of these studies was to increase a neutron yield from PF discharges by using fast deuteron beams, which are usually emitted from a pinch column and which can interact with additional D2-gas target.

7

Anisotropy of the neutron emission from PF-360 facility operated without and with solid-state targets

Czaus K., Baranowski J., Sadowski M., Skladnik-Sadowska E., Zebrowski J.

Nukleonika

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2001

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Vol. 46, suppl. 1

77--80

EN

The paper reports on detailed studies of an anisotropy of the fusion-produced neutrons emitted from the modernized PF-360 facility [10], which has been operated with a pure deuterium-gas filling, without and with some additional solidstate targets containing deuterium atoms. Under standard operational conditions, anisotropy of the neutron yield from the PF-360 facility is similar to that observed in other PF devices. For the first time the neutron emission anisotropy has been measured in the PF experiments performed with a planar cryogenic target covered with a heavy-ice (D2O) layer. Changes in the Yn(Φ)/Yn(90°) ratio, particularly for angles Φ = 0–60°, have been explained by the known features of the angular distribution of fast deuterons.