Study on strip spiral Blumlein line for the pulsed forming line of intense electron-beam accelerators

AbstractThe pulse forming line (PFL) is the key part of the intense electron-beam accelerators (IEBA), which determines the quality and characteristic of the output beam current of the IEBA. Compared with the accelerator with traditional Blumlein line, an IEBA based on strip spiral Blumlein line (SSBL) can increase the duration of the output pulse in the same geometrical dimension. But the disadvantage of the SSBL is that the output voltage waveform at the matched load may be distorted, which influences the electron beam quality. In this paper, according to the electromagnetic theory, formulas for calculating the main electric parameters of SSBL (inductance, capacitance, transmission time, and characteristic impedance) are deduced. The effect of the geometric parameters of SSBL on the slowing coefficient is analyzed. The designed condition of SSBL for the output ideal voltage pulse in the matched load is obtained by theoretical analysis. Furthermore, the Karat code is used to simulate the output voltage waveform of SSBL on the matched load for different spiral angels. At last, a couple of contrastive experiments are performed on an electron-beam accelerator based on the SSBL with water dielectric. The experimental results agree with the theoretical and simulated results.

Download Full-text

Output voltage waveform analysis of an intense electron beam accelerator based on strip spiral Blumlein line

Laser and Particle Beams ◽

10.1017/s0263034612000213 ◽

2012 ◽

Vol 30 (3) ◽

pp. 379-385 ◽

Cited By ~ 5

Author(s):

Xin-Bing Cheng ◽

Jin-Liang Liu ◽

Hong-Bo Zhang ◽

Zhi-Qiang Hong ◽

Bao-Liang Qian

Keyword(s):

Electron Beam ◽

Current Density ◽

Electron Emission ◽

Output Voltage ◽

Beam Quality ◽

Waveform Analysis ◽

Voltage Waveform ◽

Intense Electron Beam ◽

Intense Electron ◽

Spiral Type

AbstractThe Blumlein pulse forming line (BPFL) consisting of an inner coaxial pulse forming line (PFL) and an outer coaxial PFL is widely used in the field of pulsed power, especially for intense electron-beam accelerators (IEBA). The output voltage waveform determines the quality and characteristics of the output beam current of the IEBA. Comparing with the conventional BPFL, an IEBA based on a strip spiral type BPFL can increase the duration of the output voltage in the same geometrical volume. However, for the spiral type BPFL, the voltage waveform on a matched load may be distorted, which influences the electron-beam quality. In this paper, the output waveform of an IEBA based on strip spiral BPFL is analyzed. It is found that there is fluctuation on the flattop of the main pulse, and the flatness is increased with the increment of the output voltage. According to the time integrated pictures of the cathode holder during the operation of the IEBA, the electron emission of the cathode holder is one of the reasons to cause the variance of the flatness. Furthermore, the distribution of the current density of spiral middle cylinder of the BPFL is calculated by using electromagnetic simulation software, and it is obtained that the current density is not uniform, and which leads to the nonuniformity of the impedance of BPFL. Meanwhile, when the nonuniformity of the BPFL is taken into account, the operation of the whole accelerator is simulated using a circuit-simulation code called PSpice. It is obtained that the nonuniformity of the BPFL influences the flatness of the output voltage waveform. In order to get an ideal square pulse voltage waveform and to improve the electron beam quality of such an accelerator, the uniformity of the spiral middle cylinder should be improved and the electron emission of the cathode holder should be avoided. The theoretical analysis and simulated output voltage waveform shows reasonable agreement with that of the experimental results.

Download Full-text

Effect of a transition section between the Blumlein line and a load on the output voltage of gigawatt intense electron-beam accelerators

Physical Review Special Topics - Accelerators and Beams ◽

10.1103/physrevstab.12.110401 ◽

2009 ◽

Vol 12 (11) ◽

Cited By ~ 3

Author(s):

Xin-Bing Cheng ◽

Jin-Liang Liu ◽

Yu Zhang ◽

Jia-Huai Feng ◽

Bao-Liang Qian

Keyword(s):

Electron Beam ◽

Output Voltage ◽

Transition Section ◽

Intense Electron Beam ◽

Blumlein Line ◽

Intense Electron

Download Full-text

Improving the output voltage waveform of an intense electron-beam accelerator based on helical type Blumlein pulse forming line

Physical Review Special Topics - Accelerators and Beams ◽

10.1103/physrevstab.13.070402 ◽

2010 ◽

Vol 13 (7) ◽

Cited By ~ 5

Author(s):

Xin-Bing Cheng ◽

Jin-Liang Liu ◽

Hong-Bo Zhang ◽

Jia-Huai Feng ◽

Bao-Liang Qian

Keyword(s):

Electron Beam ◽

Output Voltage ◽

Voltage Waveform ◽

Intense Electron Beam ◽

Intense Electron

Download Full-text

Effect of transition section between the main switch and middle cylinder of Blumlein pulse forming line on the diode voltage of intense electron-beam accelerators

Laser and Particle Beams ◽

10.1017/s0263034609990103 ◽

2009 ◽

Vol 27 (3) ◽

pp. 439-447 ◽

Cited By ~ 11

Author(s):

X.-B. Cheng ◽

J.-L. Liu ◽

B.-L. Qian ◽

J.-D. Zhang

Keyword(s):

Electron Beam ◽

Rise Time ◽

Circuit Simulation ◽

Voltage Waveform ◽

Transition Section ◽

Intense Electron Beam ◽

Plateau Time ◽

Matching Load ◽

Intense Electron ◽

Diode Voltage

AbstractThe rise-time of the pulse on the diode of the intense electron-beam accelerators (IEBA) is one of the important factors that affect the quality and characteristic of the output beam current of the IEBA. In this paper, effect of the transition section between the main switch and middle cylinder of strip spiral Blumlein line (SSBL) on the diode voltage of IEBA is analyzed in theory, based on the theoretical analysis of the wave propagation along the Blumlein pulse forming line (BPFL), the traveling time of the transition section has a great effect on the rise-time, the plateau-time, and the fall-time of the output voltage at the matching load. Furthermore, the operation of the whole accelerator consisting of the primary energy-storage capacitor, the Tesla transformer, a main switch, the transition section, BPFL, and a resistive load was simulated using a circuit-simulation code called PSpice, and the dependence of the output voltage on the inductance of the main switch and the transition section was obtained. It was found from the wave propagation theory and the circuit simulation using computer results that the wave traveling time of the transition section between the main switch and the middle cylinder of the SSBL influences considerably the rise-time, plateau-time, and fall-time of the voltage waveform at the matching load. In order to get an ideal square pulse voltage waveform at the matching load and to improve the electron beam quality of such an accelerator, the wave traveling time of the transition section should be designed as soon as possible. At last, a couple of contrastive experiments are performed on two kinds of IEBA. The experimental results agree with the theoretical analysis and simulated results.

Download Full-text

Operating characteristics of intense electron beam accelerator at different load conditions

Laser and Particle Beams ◽

10.1017/s0263034612000456 ◽

2012 ◽

Vol 30 (4) ◽

pp. 531-539 ◽

Cited By ~ 1

Author(s):

Xin-Bing Cheng ◽

Jin-Liang Liu ◽

Zhi-Qiang Hong ◽

Bao-Liang Qian

Keyword(s):

Electron Beam ◽

Output Voltage ◽

Vacuum Chamber ◽

Electrical Insulation ◽

Load Voltage ◽

Output Terminal ◽

Surface Flashover ◽

Intense Electron Beam ◽

Intense Electron ◽

Load Conditions

AbstractAs the development of the pulsed power technology, high voltage pulse transformer (HVPT) is usually used instead of Marx generator as a charging device for the pulse forming line (PFL) of intense electron-beam accelerator (IEBA), and which make the IEBA compact. However, during the operation of the IEBA, the HVPT may be destroyed for the failure of electrical insulation and the over-voltage. So in this paper, the output voltage characteristics of IEBA, characteristics of the voltage at the output terminal of HVPT at four kinds of load conditions are analyzed, including load matching, load short, load open, and surface flashover in the vacuum chamber. It is found that load short, load open, and surface flashover in vacuum chamber will affect the voltage at the output terminal of HVPT, and an oscillation wave could be formed, which affect the electrical insulation of HVPT and decrease the lifetime of HVPT. Meanwhile, the waveform of the load voltage is also modified, especially at the conditions of load open and surface flashover in vacuum chamber. When the load is open, the amplitude of the output main pulse of IEBA is twice the charging voltage of BPFL. However, the amplitude of the output pulse of IEBA is modified by the voltage at the output terminal of HVPT, and the resistance of main switch channel has a great effect on the amplitude of the load voltage. When surface flashover occurs in the vacuum chamber, the pulse duration of the output voltage will be decreased. So, during the operation of IEBA, load short, load open and surface flashover in vacuum chamber should be avoided.

Download Full-text