Current loss of magnetically insulated coaxial diode with cathode negative ion

Zhu, Danni; Zhang, Jun; Zhong, Huihuang; Gao, Jingming; Bai, Zhen

doi:10.1088/1674-1056/27/2/020501

Cited by 5 publications

(1 citation statement)

References 30 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The external solenoid used for electron magnetization, provides magnetic field with amplitude up to 0.8 T. The red lines represented the electron beam trajectories overlapped with the corresponding magnetic lines profile. A shield hoop was used to protect the insulator from this reverse electrons bombardment [11]. The length of the magnetic solenoid and the anode tube including the collector were 72 mm and 418 mm, respectively.…”

Section: Methodsmentioning

confidence: 99%

Investigating emission characteristics and plasma properties in a long-pulse magnetically insulated coaxial diode with different cathode materials

Zhu¹,

Cui²,

Meng³

et al. 2023

Phys. Scr.

View full text Add to dashboard Cite

Magnetically insulated coaxial diodes are widely used in O-type high power microwave device for intensive annular electron beam generation. This study reports on a series of electrical and optical measurements on a long-pulse magnetically insulated coaxial diodes in which the emission characteristics and the plasma properties were observed. The impact of cathode material, blade angle, diode voltage and guiding magnetic field on the emission characteristics and the plasma properties of six types of annular cathodes were studied. Two configurations of these cathodes have been used, one with a sharp edge for aluminum, bronze, graphite, stainless-steel, silicon-aluminum alloy and another metal–dielectric. The impressing diode performance was achieved with the metal-dielectric cathode characterized on the excellent emission characteristics and plasma properties. Moreover, high voltage and small blade angle are beneficial to the emission capability and emission uniformity. For the cathode with smaller blade angle, its axial plasma expansion velocity is smaller during the pulse plateau. The strong magnetic field or the large diode voltage is confirmed to reduce the axial and radial expansion velocities.

show abstract

Section: Methodsmentioning

confidence: 99%

Investigating emission characteristics and plasma properties in a long-pulse magnetically insulated coaxial diode with different cathode materials

Zhu¹,

Cui²,

Meng³

et al. 2023

Phys. Scr.

View full text Add to dashboard Cite

show abstract

Analyses of bombardment traces on the tube head of a relativistic backward wave oscillator

Xiao

Deng

et al. 2019

Physics of Plasmas

View full text Add to dashboard Cite

In the repetitive experiments of relativistic backward wave oscillators operating at either low or high magnetic field, we found that the spiral traces appeared on the surfaces of the tube heads (entrance to the reflector and slow wave structure). Three possible causes: electrons emitted from the cathode base, cathode plasma, and cathode negative ion, are analyzed. Among them, the cathode negative ion is the most likely factor leading to the traces. The negative ions are generated by electron impact-ionization and ion impact-ionization of molecules that are desorbed from the cathode by the Ohmic heating of explosive electron emission. Due to the larger mass of negative ion, it cannot be restricted effectively by the magnetic field and will basically move along the electric field line. Many negative ions bombard the tube head with a Larmor radius of several centimeters, and the traces are connected to form spiral lines. The viewpoint of cathode negative ion current is further confirmed by the comparative experiments that show that a graphite cathode after being immersed in water for 12 h results in heavier traces, while a larger anode and cathode gap leads to slighter traces. Some suggestions are provided to reduce the production and the effect of cathode negative ion current.

show abstract

Theoretical analysis and experimental verification of electron beam transmission with low guiding magnetic field in V-band coaxial transit-time oscillator

Deng

Ling

et al. 2021

Physics of Plasmas

View full text Add to dashboard Cite

The transmission of an electron beam with a low magnetic field is theoretically and experimentally investigated. In a high frequency band, due to a narrow tunnel of the electron beam, the transmission of the electron beam highly depends on beam parameters. The transmission of the electron beam is analyzed through the beam envelope equation, and accordingly, the relationship between beam parameters and transversal diffusion of the electron beam is derived. By particle-in-cell simulation, the influence of the current density, loading position, and guiding magnetic field on the electron beam is discussed. An electron beam with a beam voltage of 400 kV and a beam current of 5.0 kA in the guiding magnetic field of 1.0 T is applied in the experiment. The experiment consists of the electron beam bombardment on the nylon target and measurements of the beam current. The experimental results show that the electron beam can be stably and uniformly transmitted at a low loss under the given conditions.

show abstract

Current loss of magnetically insulated coaxial diode with cathode negative ion

Cited by 5 publications

References 30 publications

Investigating emission characteristics and plasma properties in a long-pulse magnetically insulated coaxial diode with different cathode materials

Investigating emission characteristics and plasma properties in a long-pulse magnetically insulated coaxial diode with different cathode materials

Analyses of bombardment traces on the tube head of a relativistic backward wave oscillator

Theoretical analysis and experimental verification of electron beam transmission with low guiding magnetic field in V-band coaxial transit-time oscillator

Contact Info

Product

Resources

About