Propagation of individual plasma spots on cathode surface by high-current discharge process

Liu, Limin; Liu, Lie; Xu, Qifu; Chang, Lei; Wan, Hong; Wen, Jihong

doi:10.1016/j.physleta.2009.01.045

Cited by 4 publications

(5 citation statements)

References 14 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Electron emission will be initiated at the emitters closest to the anode. Once these emitters generate electrons, the microscopic electric field at the neighbouring emitters will be weakened due to the shielding effect of the electric field [46]. This leads to the failure of electron emission at the neighbouring emitters.…”

Section: Resultsmentioning

confidence: 99%

“…The difference between the diode impedances using two cathodes is attributed to the effects of cathode plasma expansion. To analyse the difference in diode impedances, the curves of cathode plasma expansion velocities (v p ) are plotted in figure 6(c), according to the method described in our previous paper [46]. The plasma expansion of the TiO 2 /carbon fibre cathode develops into a stable stage at ∼0.25 µs, which is obviously shorter than that of carbon fibre cathode (∼0.5 µs).…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Cold atmospheric pressure plasma jet prepares TiO₂ coating on carbon fibre for field emission and explosive electron emission

Zhiwei¹,

Ma²,

Liu³

et al. 2021

J. Phys. D: Appl. Phys.

Self Cite

View full text Add to dashboard Cite

As the 'heart' of high-current vacuum electronic devices, explosive emission cathodes play an important role in their applications. In this work, a titanium dioxide (TiO 2 )/carbon fibre cathode prepared by a cold atmospheric plasma jet is reported. TiO 2 on the carbon fibre surface prepared by an atmospheric plasma jet is at the mixture of anatase and rutile phases. The field enhancement factor of the TiO 2 /carbon fibre cathode is 6681, which is over ten times higher than that of the carbon fibre cathode. Furthermore, the TiO 2 coating slows the diode impedance collapse and decreases the cathode plasma expansion velocity from 1.5-2.0 to 1.0-1.5 cm µs −1 , which is explained by a cathode plasma model. The surface of the TiO 2 /carbon fibre cathode is covered by 1.6 cm 2 plasma, far exceeding that of the carbon fibre cathode (1.1 cm 2 ), which enables uniform explosive electron emission. The obtained results show that TiO 2 /carbon fibre cathodes prepared by cold atmospheric plasma jets will be potential candidates as high-current explosive electron emitters.

show abstract

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Cold atmospheric pressure plasma jet prepares TiO₂ coating on carbon fibre for field emission and explosive electron emission

Zhiwei¹,

Ma²,

Liu³

et al. 2021

J. Phys. D: Appl. Phys.

Self Cite

View full text Add to dashboard Cite

show abstract

“…The microcraters on the anode target are perhaps produced by electron microblobs from the cathode due to the appearance of individual plasma spots on cathode surface (Li et al, 2009d). Thus, it seems likely that there are microregions at the anode where the beam current density is higher than the average current density.…”

Section: Structure Of the Anode Surfacementioning

confidence: 99%

Layer structure, plasma jet, and thermal dynamics of Cu target irradiated by relativistic pulsed electron beam

Liu

Cheng

et al. 2009

Laser Part. Beams

Self Cite

View full text Add to dashboard Cite

This paper, based on a relativistic electron-beam accelerator with inductive energy accumulation, investigates the layer structure, plasma jet, and thermal dynamics of Cu target under the irradiation of pulsed electron beam (350 kV, 4 kA, 300 ns). A description of a relativistic electron beam source with a carbon fiber cathode is presented. After the electron-beam irradiation at 13 J/cm 2 energy density, microcraters with 0.5-1 mm diameter appeared on the target surface, and the target cross section is characterized by multilayer structures with a 20 mm thickness melting layer and a cellular layer. Further, it was found that the carbon content increased significantly not only on the target surface but also on the cross section. The gas liberation per pulse induced by electron beam is analyzed. A good agreement between the experimental and calculated perveances was observed, with the exception at the end of the accelerating pulse possibly due to the participation of ion flow from the anode target. In the pulsed emission, there existed material transfer from anode to cathode, which is observed by the identification of elemental compositions on cathode surface. As the beam energy is deposited on target surface, the anode plasma jet is generated, and expands toward the cathode at a velocity of 3 cm/ms. By solving the one-dimensional heat equation, 10 9 K/s heating rate and 10 7 K/m temperature gradient can be obtained. After the heating of pulsed electron beam, the thermal conduction is dominant, with a cooling rate on the order of 10 7 K/s. The relativistic electron beam sources may provide a potential development for target experiments and high energy density physics.

show abstract

“…Carbon-fibers are usually utilized to reinforce composite materials due to their superior mechanical properties such as high specific strength modulus, low expansion coefficient, small density, good environmental compatibility, long-term durability, and high resistance to chemical corrosion (Li et al, 2009a;Pan et al, 2010;Tiwari et al, 2011). Carbon-fibers are used in vacuum electronic tubes because this type of highcurrent electron beam source typically has a long life-time and low work function while producing a uniform plasma across the cathode surface at a small plasma expansion velocity (Li et al, 2012;2009c;2009d). By combining CsI with carbon-fibers, strong plasmas can be generated from the cathode surface under slower plasma expansion while the diode gap during the main voltage pulse is almost unchanged (Li et al, 2009b).…”

Section: Introductionmentioning

confidence: 99%

Plasma-target surface interaction during non-equilibrium plasma irradiation at atmospheric pressure: Generation of dusty plasma

Liu

Zhang

et al. 2013

Laser Part. Beams

Self Cite

View full text Add to dashboard Cite

The remaining challenges, developing the relativistic electron beam sources, stimulate the investigations of cathode materials. Carbon-fiber-aluminum composite is the most appropriate cathode materials to construct the robust relativistic electron beam sources. Carbon-fiber-aluminum composite is treated by a non-equilibrium atmospheric plasma torch with a copper electrode based on high-voltage gas discharge. The axial and radial distributions of the plasma torch temperature are measured to determine the optimal treatment temperature and location. Copper-oxide particles with diameters of less than 1 µm are deposited onto the surface of the carbon-fibers and a layer of copper-oxide covers the entire surface as the treatment time is increased. Raman spectroscopy suggests that although the locations of the D and G band are similar, the areas of the D and G bands increase after the plasma treatment due to the reduced graphite crystalline size in the carbon-fibers. Analysis of the copper electrode surface discloses materials ablation arising from the discharge which releases copper from the source. Our results reveal that the atmospheric plasma torch generated by high-voltage discharge is promising in the surface modification of the carbon-fiber-reinforced aluminum composite. Further, the plasma produced by atmospheric plasma torch is dusty plasma, due to the participation of liberated copper particles. The plasma torch was analyzed by fluid dynamics, in terms of plasma density, plasma expansion velocity, and internal pressure, and it was found that the plasma produced by atmospheric torch is supersonic flow.

show abstract

Propagation of individual plasma spots on cathode surface by high-current discharge process

Cited by 4 publications

References 14 publications

Cold atmospheric pressure plasma jet prepares TiO₂ coating on carbon fibre for field emission and explosive electron emission

Cold atmospheric pressure plasma jet prepares TiO₂ coating on carbon fibre for field emission and explosive electron emission

Layer structure, plasma jet, and thermal dynamics of Cu target irradiated by relativistic pulsed electron beam

Plasma-target surface interaction during non-equilibrium plasma irradiation at atmospheric pressure: Generation of dusty plasma

Contact Info

Product

Resources

About

Propagation of individual plasma spots on cathode surface by high-current discharge process

Cited by 4 publications

References 14 publications

Cold atmospheric pressure plasma jet prepares TiO2 coating on carbon fibre for field emission and explosive electron emission

Cold atmospheric pressure plasma jet prepares TiO2 coating on carbon fibre for field emission and explosive electron emission

Layer structure, plasma jet, and thermal dynamics of Cu target irradiated by relativistic pulsed electron beam

Plasma-target surface interaction during non-equilibrium plasma irradiation at atmospheric pressure: Generation of dusty plasma

Contact Info

Product

Resources

About

Cold atmospheric pressure plasma jet prepares TiO₂ coating on carbon fibre for field emission and explosive electron emission

Cold atmospheric pressure plasma jet prepares TiO₂ coating on carbon fibre for field emission and explosive electron emission