Nanosecond electron accelerator

 

(57) Abstract:

The invention relates to accelerator technology and can be used to form the electron beam. Nanosecond electron accelerator contains a high-voltage pulse generator with a semiconductor circuit breaker, vacuum diode that uses a metal-ceramic cathode, the composition of which is chosen so that a temporary delay tCthe beginning of the current vacuum diode on voltage and the rise time of the power semiconductor circuit breaker taboutconsistent with the condition tC~ 0,7 tabout. The technical result is to increase the efficiency of energy transfer in the beam and a decrease in the proportion of low-energy electrons in the generated beam. table 2., 2 Il.

The invention relates to accelerator technology and can be used to produce beams of electrons.

The creation of powerful nanosecond generators high-voltage pulses on semiconductor opening switch current with a pulse repetition rate up to kHz and a service life of 1010-1011pulses [1, 2] have necessitated the development of promising technologies for electron accelerators with generators [3, 4].

Od the high proportion of low-energy electrons generated in the beam when using metal (MDM) cathodes [5].

The closest analogue is the technical solution described in [6]. The invention relates to accelerator technology and can be used for the formation of nanosecond electron beam. Metal-ceramic cathode was tested at a frequency of nanosecond electron accelerator URT is 0.5. Known nanosecond electron accelerator contains a high-voltage pulse generator with solid-state circuit breaker and vacuum diode that uses a metal-ceramic cathode.

The aim of the invention is to increase the efficiency of energy transfer in the beam and a decrease in the proportion of low-energy electrons in the generated beam.

This objective is achieved in that in the nanosecond electron accelerator comprising a generator of high voltage pulses with semiconductor circuit breaker and vacuum diode that uses a metal-ceramic cathode (MK cathode), the composition of the metal-ceramic cathode is chosen so that a temporary delay tCthe beginning of the current vacuum diode on voltage and the rise time of the power semiconductor circuit breaker taboutconsistent with the condition tC~ 0,7 tabout.

MK cathode is the way the e particles, the part which comes to the surface. MK cathode is placed on the metal cottagesetere (Fig.1). Due to the substantial difference in the temperature coefficients of linear expansion of the ceramic and metal during cooling of such system after synthesis around the metal particles are formed of micro-cavities, which serve as suppliers of gas at the surface formation of plasma at MK the cathode.

When working MK cathodes have a temporary delay t3the beginning of the current in the diode relative to the voltage, and the value of t3can be controlled by changing the composition of the MK cathode [7]. The choice of the moment of load is connected in the stage of rapid growth of the impedance of the circuit breaker of any type can improve the working conditions of the circuit breaker and to increase output power [8].

In Fig.1 presents a diagram of nanosecond electron accelerator, where 1 is the vacuum insulator, 2 - catalogization, 3 - MK plate.

The accelerator works as follows (see Fig.1).

The high-voltage pulse generator is formed by a pulse of high voltage and simultaneously applied to the vacuum diode. On the surface MK cathode electric field appears.

Emitting plasma voznikayuthih, facing surface of the mark plate 3, provides the necessary electron emission and electrical contact with metal base. Due to the delay between the application of the pulse voltage and current occurrence of a vacuum diode semiconductor breaker in the fast growth of impedance loaded on the load with a high impedance, thus increasing the efficiency of energy transfer in the beam and to reduce the share of low-energy electrons in the generated beam.

The proposed solution has been experimentally tested. Used nanosecond accelerator URT-0,5 [4]: accelerating voltage U=500 kV, the pulse duration at half-height tu~ 50 NS, the duration of the pulse tf~ 0,1-0,9= 46 NS, the frequency of operation f=200 Hz. The design of the cathodic site similar to [6] . The parameters investigated types MK cathodes are shown in table. 1. The cathode 1885 consists of ceramics Al2ABOUT3with a diameter of metal particles of 9 μm, the number of these particles in 1 cm2is 1900 PCs/cm2. The cathode 1889 consists of ceramics Al2ABOUT3with a diameter of metal particles of 9 μm, the number of particles in 1 cm2is 40000 PCs/cm2. The cathode 11-1 consists of ceramics Al2ABOUT3with Amici TiO2with a diameter of metal particles of 9 μm, the number of particles in 1 cm2is 4020 PCs/cm2.

Since the rise time of the power semiconductor circuit breaker is in the range tabout~ 30 NS (for diodes NLL), the increase in t3leads first to an increase in output power, and then to reduction (table. 2). The maximum efficiency of energy transfer to the electron beam was at MK cathode 1891 (PL. 2). There is almost a linear dependence of the efficiency of energy transfer from tC. However, for MK plate 1891 increase in efficiency is achieved by increasing the share of low-energy electrons generated on a falling edge of the voltage, as the maximum power lags behind the maximum voltage (Fig.2). Therefore, the optimal value of the time delay is tC~ 0,7 tabout.

Thus, the use of MK cathode allows to obtain a high output power of the accelerator at higher accelerating voltage than when using MDM cathode [5].

Literature

1. Yu.A. Kotov, G. A. each month should text month, S. N. Rukin et al., Digest of Technical Papers 9th IEEE Pulsed Power Conf., Albuquerque, 1993, vol. I, pp. 134-139.

2. Yu.A. Kotov, G. A. each month should text month, S. R. Korzhenevskii et al., Proc. 10th IEEE Pulsed Power Conf, 1995, Santa Fe, New Mexico, USA, pp. 1231-1234.

3. Y. A. Kotov, S. Yu Socv, Century Century Ladokhin, D. L. Kuznetsov and others, PTE, 2000, 5, S. 71-76.

6. Y. A. Kotov, S. Y. Sokovnin, M. E. Baltin "metal-ceramic cathode, RF Patent 2158982.

7. Yu. A. Kotov, S. Yu. Sokovnin, M. E. Balezin, "Proc. of the 12th Symp. on High Current Electronics, September 25-29, 2000,Tomsk, pp. 38-42.

8. Y. A. Kotov, A. C. Lucinschi, "In kN.: Physics and technology of high-power pulsed systems" Ed. by E. P. Velikhov. M.: Energoatomizdat, 1986, S. 189-210.

Nanosecond electron accelerator comprising a generator of high voltage pulses with semiconductor circuit breaker and vacuum diode that uses a metal-ceramic cathode, characterized in that the composition of the metal-ceramic cathode is chosen so that a temporary delay tCthe beginning of the current vacuum diode on voltage and the rise time of the power semiconductor circuit breaker taboutconsistent with the condition tC~ 0,7 tabout.

 

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SUBSTANCE: proposed method intended to ensure better alignment of electron-optical system components, or more precisely, to align holes of control grid with those of transit-time channels of anode for easier current flow through device includes soldering of insulators, control grid, and seating flange together at preset elevation of grid above flange; installation of assembled cathode unit at preset gap between cathodes and control grid; alignment of cathodes with hole in the latter; fixation of cathode unit in insulator by spot welding; installation of assembled gun into device against seating diameters and pins in key holes of anode pole shoe and seating flange, the latter being composed of two parts of which one having key holes and seating diameter is movable and mounted on second fixed part prior to installing gun into device; after that key holes are aligned with grid holes against angle of turn and secured on fixed part.

EFFECT: enhanced precision of assembly.

2 cl, 3 dwg

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