Plasma effects on electron beam focusing and microwave emission in a virtual cathode oscillator

1998 ◽  
Vol 26 (4) ◽  
pp. 1314-1321 ◽  
Author(s):  
M. Yatsuzuka ◽  
M. Nakayama ◽  
M. Tanigawa ◽  
S. Nobuhara ◽  
D. Young ◽  
...  
Keyword(s):  
Electron Beam ◽  
Virtual Cathode ◽  
Microwave Emission ◽  
Beam Focusing ◽  
Plasma Effects

Effects of electron beam focusing on virtual cathode formation in virtual cathode oscillator

2016 ◽  
Author(s):  
Se-Hoon Kim ◽  
Chang-Jin Lee ◽  
Jae-Ho Rhee ◽  
Young-Maan Cho ◽  
Ji-Eun Baek ◽  
...  
Keyword(s):  
Electron Beam ◽  
Virtual Cathode ◽  
Beam Focusing

Point-Cathode Electron Gun Using Electron-Beam Bombardment for Cathode Tip Heating

1990 ◽  
Vol 48 (1) ◽  
pp. 198-199
Author(s):  
Ryo Iiyoshi ◽  
Susumu Maruse ◽  
Hideo Takematsu
Keyword(s):  
Electron Beam ◽  
Tungsten Wire ◽  
Local Heating ◽  
Electron Gun ◽  
Original Position ◽  
Beam Power ◽  
Radius Of Curvature ◽  
High Brightness ◽  
Beam Focusing ◽  
Time Operation

Point cathode electron gun with high brightness and long cathode life has been developed. In this gun, a straightened tungsten wire is used as the point cathode, and the tip is locally heated to higher temperatures by electron beam bombardment. The high brightness operation and some findings on the local heating are presented.Gun construction is shown in Fig.l. Small heater assembly (annular electron gun: 5 keV, 1 mA) is set inside the Wehnelt electrode. The heater provides a disk-shaped bombarding electron beam focusing onto the cathode tip. The cathode is the tungsten wire of 0.1 mm in diameter. The tip temperature is raised to the melting point (3,650 K) at the beam power of 5 W, without any serious problem of secondary electrons for the gun operation. Figure 2 shows the cathode after a long time operation at high temperatures, or high brightnesses. Evaporation occurs at the tip, and the tip part retains a conical shape. The cathode can be used for a long period of time. The tip apex keeps the radius of curvature of 0.4 μm at 3,000 K and 0.3 μm at 3,200 K. The gun provides the stable beam up to the brightness of 6.4×106 A/cm2sr (3,150 K) at the accelerating voltage of 50 kV. At 3.4×l06 A/cm2sr (3,040 K), the tip recedes at a slow rate (26 μm/h), so that the effect can be offset by adjusting the Wehnelt bias voltage. The tip temperature is decreased as the tip moves out from the original position, but it can be kept at constant by increasing the bombarding beam power. This way of operation is possible for 10 h. A stepwise movement of the cathode is enough for the subsequent operation. Higher brightness operations with the rapid receding rates of the tip may be improved by a continuous movement of the wire cathode during the operations. Figure 3 shows the relation between the beam brightness, the tip receding rate by evaporation (αis the half-angle of the tip cone), and the cathode life per unit length, as a function of the cathode temperature. The working life of the point cathode is greatly improved by the local heating.

Influence of positive ions on oscillatory processes in an electron beam with virtual cathode

2006 ◽  
Vol 49 (10) ◽  
pp. 769-778
Author(s):  
R. A. Filatov ◽  
Yu. A. Kalinin ◽  
A. E. Khramov ◽  
D. I. Trubetskov
Keyword(s):  
Electron Beam ◽  
Virtual Cathode ◽  
Positive Ions ◽  
Oscillatory Processes

Higher harmonics generation in relativistic electron beam with virtual cathode

2014 ◽  
Vol 21 (9) ◽  
pp. 093105 ◽  
Author(s):  
S. A. Kurkin ◽  
A. A. Badarin ◽  
A. A. Koronovskii ◽  
A. E. Hramov
Keyword(s):  
Electron Beam ◽  
Relativistic Electron ◽  
Relativistic Electron Beam ◽  
Virtual Cathode ◽  
Higher Harmonics ◽  
Harmonics Generation

V-Shaped Potential Distribution with a Virtual Cathode Generated by an Electron Beam Injection

1982 ◽  
Vol 51 (2) ◽  
pp. 650-657 ◽  
Author(s):  
Hiroharu Fujita ◽  
Shinya Yagura ◽  
Eiichi Yamada ◽  
Akira Aoyagi
Keyword(s):  
Electron Beam ◽  
Potential Distribution ◽  
Virtual Cathode ◽  
Beam Injection

Method of Locating the Axis of a Magnetic Field for Electron‐Beam Focusing

1968 ◽  
Vol 39 (10) ◽  
pp. 4573-4580 ◽  
Author(s):  
H. Nishihara ◽  
M. Terada
Keyword(s):  
Magnetic Field ◽  
Electron Beam ◽  
Beam Focusing
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