Pinching evidences in a miniature plasma focus with fast pseudospark switch

Hassan, S. M.; Zhang, T; Patran, A.; Rawat, Rajdeep Singh; Springham, S. V.; Tan, T.L.; Wong, D.; Wang, W; Lee, S; Грибков, В. А.; Mohanty, S. R.; Lee, P

doi:10.1088/0963-0252/15/4/004

Cited by 36 publications

(12 citation statements)

References 23 publications

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“…The maximum yield of (1.06 ± 0.13) × 10 6 neutrons/shots at 9 mb deuterium gas pressure has already been observed (Silva et al 2003) from a fast plasma focus at 400 J of bank energy. The pinching evidence has been observed in the PF devices operated at very low bank energies of ≈100 J (Soto et al 2001), of 32-102 J (Silva et al 2002), of 50 J (Moreno et al 2003), of 50-70 J (Silva et al 2004) and of 58-160 J (Hassan et al 2006). The generation of extreme ultraviolet (Mohanty et al 2006) as a compact and competent source for lithography, emission of soft x-rays (Mohammadi et al 2007) useful for lithography and production of hard x-rays (Moreno et al 2006, Lorenzo et al 2007 for flash radiography have also been reported.…”

Section: Introductionmentioning

confidence: 82%

Battery powered tabletop pulsed neutron source based on a sealed miniature plasma focus device

Rout¹,

Mishra²,

Rawool³

et al. 2008

J. Phys. D: Appl. Phys.

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The development of a novel and portable tabletop pulsed neutron source is presented. It is a battery powered neutron tube based on a miniature plasma focus (PF) device having all metal-sealed components. The tube, fuelled with deuterium gas, generates neutrons because of D–D fusion reactions. The inner diameter and the length of the tube are 3.4 cm and 8 cm, respectively. A single capacitor (200 J, 4.0 µF, 10 nH) of compact size (17 cm × 15 cm × 13 cm, 6.5 kg) is used as the energy driver. A power supply system charges the capacitor to 10 kV in 10 s and also provides a 30 kV trigger pulse to the spark gap. An input of 24 V dc (7.5 A) to the power supply system is provided by two rechargeable batteries (each 12 V, 7.5 A, 20 h). The device has produced neutrons for 150 shots within a period of 120 days in a very reliable manner without purging the deuterium gas between the shots. For the first 50 shots, the average yield is (1.6 ± 0.3) × 106 neutrons/shot in 4π sr with a pulse width of 23.4 ± 3.3 ns. The estimated neutron energy is 2.47 ± 0.22 MeV. The neutron production reduces slowly and reaches the detection threshold value of 3 × 105 neutrons/shot towards the last shots. The device produces neutrons in a similar manner on evacuation and refilling. The height of the mounted PF tube with the capacitor and the spark gap is 35 cm. The complete setup comprising the capacitor with spark gap, the PF tube, the power supply system with two batteries and the control panel weighs only 23 kg.

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Section: Introductionmentioning

confidence: 82%

Battery powered tabletop pulsed neutron source based on a sealed miniature plasma focus device

Rout¹,

Mishra²,

Rawool³

et al. 2008

J. Phys. D: Appl. Phys.

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“…For most all other conditions the rise time of luminous intensity is about 200 ns. That the rapid increase in luminous intensity occurs simultaneously with the sheaths arrival at the anode tip likely indicates the occurrence of a pinch as previous research has demonstrated [43,44]. From event to event luminous intensity appears to vary by 25% due to initial asymmetry or shot to shot variation.…”

Section: μM Dpfmentioning

confidence: 53%

“…Intensely bright regions correspond to high energy and high plasma density. Regions of intense brightness at the anode tip are indicative of a pinch event, and in some cases evidence of a pinch can only be observed optically because electrical signals do not show the characteristic dip in the I t d /d trace accompanied by a simultaneous voltage spike [43,44].…”

Section: Methodsmentioning

confidence: 99%

Dynamics of two microscale DPF devices

Pollard

Duggleby²,

Staack

2015

J. Phys. D: Appl. Phys.

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Dense plasma focus (DPF) devices are coaxial transient discharge devices capable of generating plasma densities greater than 10 16 cm −3 with ion temperatures in excess of 1 keV by compression resulting from strong magnetic fields created by high pulsed current. They are predominately used for high energy particle generation, but they are also convenient for investigating pinch dynamics due to their relatively fast repetition rates. These devices have been extensively studied at length scales on the order of cm, and this work helps to bridge understanding of larger low pressure pinches and more recent moderate energy density sources with novel applications like portable sources for high energy particles. In this research, the dynamics of two significantly smaller DPF devices operating in 50-190 torr He at <5 J/pulse with anode radii of 550 μm and 100 μm have been investigated using a 50 ns gated ICCD to image discharges throughout their lifetimes. Typical discharge stages of breakdown, rundown, pinch and expansion are observed for the microscale DPF. Images during the breakdown process are compared with respect to their symmetry, the velocity of their features, and their relative pinch intensities. Applicable scaling parameters are also compared to those of other DPF devices. In addition, the applicability of Knudsen scaling to DPF operation is introduced. The images show that as the anode radius decreases, breakdown and rundown features tend towards symmetry at higher pressure and near the Paschen minimum.

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“…Some efforts have been devoted to either correcting their signals using an appropriate model [19] or using very small probe sizes when compared to the plasma sheath dimensions [20]. These methods are particularly difficult to use on very small plasma focus devices (usually portable and sub-kJ of stored energy) where the physical dimensions of the load and the plasma sheath are in the millimeter range (or even lower) [10,14,[21][22][23][24][25][26]. Additionally, some optical diagnostic methods have been used for determining some sheath properties based on single shot measurements.…”

Section: Introductionmentioning

confidence: 99%

Non-intrusive plasma diagnostics for measuring sheath kinematics in plasma focus discharges

Veloso¹,

Moreno²,

Tarifeño-Saldivia³

et al. 2012

Meas. Sci. Technol.

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The description and use of a non-perturbative optical diagnostic technique for measuring sheath movement in plasma focus are presented. The method is based on a lens that collects the light emitted by the plasma sheath which is detected by fast photodiodes. Two different circuit connections for the photodiodes are presented using either several or a single scope channels to record the photodiode signals. The technique is applied to a 300 J plasma focus with a spatial resolution of ∼0.25 mm measuring its average propagation speeds (axial and radial) as well as its detachment time and an estimated thickness. The setup required in this technique is easy to implement and cost-effective, and it can be applied in any plasma focus, regardless of its stored energy or operational gas.

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Pinching evidences in a miniature plasma focus with fast pseudospark switch

Cited by 36 publications

References 23 publications

Battery powered tabletop pulsed neutron source based on a sealed miniature plasma focus device

Battery powered tabletop pulsed neutron source based on a sealed miniature plasma focus device

Dynamics of two microscale DPF devices

Non-intrusive plasma diagnostics for measuring sheath kinematics in plasma focus discharges

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