Picosecond pulse source device with adjustable amplitude and fast rising edge

Abstract

The invention discloses a picosecond pulse source device with adjustable amplitude and a fast rising edge, and belongs to the technical field of electronic circuits. According to the pulse source device, the fast rising edge and narrow pulse width of a positive pulse signal are ensured, and meanwhile, amplitude and repetition frequency adjustment is carried out on the pulse signal generated by the Marx circuit; two triggering signal modes of internal triggering and external triggering are supported, and the internal triggering signal generating circuit can generate internal triggering signals with adjustable repetition frequency; the Marx circuit outputs a pulse signal after receiving the trigger signal, the Marx circuit is debugged, the output is reversely connected, a high-amplitude and fast-rising-edge positive pulse signal is generated, and the positive pulse signal with the adjustable amplitude is output through the amplitude adjusting module. The device disclosed by the invention is integrated in a cavity, so that the reliability and convenience of the pulse source are enhanced; the invention has the advantages of simple operation, small size and the like, is beneficial to modularization, has adjustable amplitude and faster rising edge, and can meet the requirements of amplitude and repetition frequency conditions in different application scenes.

Description

Technical Field

[0001] The present invention belongs to the technical field of electronic circuits, relates to the design of a pulse signal source system, and in particular to a picosecond pulse source device with adjustable amplitude and fast rising edge. Background Art

[0002] Pulse power technology, with its high power and short pulse width, offers unique and novel benefits. Demand for high-voltage, high-power, picosecond-level narrow pulse sources with adjustable repetition rates is increasing in numerous fields, including ground-penetrating radar, sterilization, industrial processing, and laser-gated imaging. For example, in the laser cutting industry, pulse repetition rate and amplitude can be adjusted to accommodate the processing needs of different materials, such as metals, ceramics, and composites.

[0003] Currently, most high-power pulse sources have fixed amplitudes and repetition rates, and their rise times are very slow. They require an external signal generator to provide a trigger signal, and the high-voltage DC power supply also requires external instrument input. This makes them cumbersome to use and inconvenient to carry. Industries such as medical, military and aerospace, environmental and energy, and agriculture and food processing are increasingly demanding picosecond pulse sources with adjustable amplitude and repetition rate. Therefore, a solution is necessary to meet the current application needs of various industries.

[0004] A Chinese patent application with patent application number CN 2019112070474 and invention name “Output adjustable nanosecond pulse source based on avalanche transistor cascade circuit” discloses a control circuit, a control method and a corresponding pulse source system for a pulse output source. Each unit of the system includes an avalanche transistor, an avalanche transistor for switch control (hereinafter referred to as: controllable transistor), a current limiting resistor and a charging capacitor; wherein the base of the controllable transistor in each of the above units is used to receive a control signal, so that the charging capacitor in the unit can be excluded from the discharge capacitor group to achieve the adjustment of the output power of the pulse output source. However, the maximum pulse amplitude of this prior art is 272V, and the rising edge and pulse width are also in the nanosecond level, which cannot meet the use scenarios with higher amplitudes and narrower pulse widths.

[0005] A Chinese patent application with the patent application number CN2022109470524, entitled "A Method and Apparatus for Generating a Frequency-Adjustable Bipolar Gaussian Pulse Source," discloses a method and apparatus for generating a frequency-adjustable bipolar Gaussian pulse source. The device incorporates a capacitor circuit corresponding to a variety of frequencies. Frequency adjustment is achieved by adjusting the capacitance value to the value corresponding to the desired frequency, ultimately enabling the generation and frequency switching of 50MHz, 100MHz, 150MHz, and 230MHz pulses. However, this prior art cannot achieve amplitude adjustment, and the pulse width is greater than 2ns. Excessive pulse width can affect the accuracy of ground-penetrating radar. Summary of the Invention

[0006] The purpose of the present invention is to overcome the above-mentioned defects of the prior art and provide a picosecond pulse source device with adjustable amplitude and fast rising edge.

[0007] The technical problem proposed by the present invention is solved as follows:

[0008] A picosecond pulse source device with adjustable amplitude and fast rising edge, comprising a power conversion circuit, an internal trigger signal generating circuit, an internal and external trigger signal switching circuit, a Marx circuit and a pulse voltage amplitude adjustment module;

[0009] The power conversion circuit is used to convert AC power into DC power for use by circuits and modules within the device;

[0010] The internal trigger signal generating circuit is used to generate the internal trigger signal for triggering the Marx circuit. The internal trigger signal can realize repetition frequency adjustment.

[0011] The internal and external trigger signal switching circuit is used to realize the selection of the internal trigger signal or the external trigger signal, and trigger the Marx circuit based on the selected trigger signal;

[0012] After receiving the trigger signal, the Marx circuit is used to generate a fast rising edge picosecond pulse signal;

[0013] The pulse voltage amplitude adjustment module adjusts the pulse voltage amplitude of the fast rising edge picosecond pulse signal and then outputs it.

[0014] Furthermore, the power conversion circuit converts the 220V AC power supply into DC 250V, 12V and 5V power supplies, of which the 250V and 12V power supplies are used by the Marx circuit, and the 5V power supply is used by the internal trigger signal generating circuit and the internal and external trigger switching circuit.

[0015] Furthermore, the internal trigger signal generating circuit is implemented based on a timer chip and can generate a TTL square wave signal with a frequency of 50Hz-1kHz.

[0016] Furthermore, in the internal trigger signal generating circuit, a 5V power supply is supplied through a decoupling capacitor C20 and is connected to the power pin and reset pin of the timer chip, and the ground pin of the timer chip is grounded; a resistor R21, a diode D2, a variable resistor R23 and a capacitor C21 are connected in series in sequence, the resistor R21 is connected to the 5V power supply, and the capacitor C21 is grounded; the cathode of the diode D1 is connected to one end of the resistor R22, the anode of the diode D1 is connected to the cathode of the diode D2, and the other end of the resistor R22 is respectively connected to the anode of the diode D2 and the discharge pin of the timer chip; the trigger pin and the threshold pin of the timer chip are interconnected, and then connected between the variable resistor R23 and the capacitor C21; the control power pin of the timer chip is grounded through the capacitor C22 to stabilize the reference voltage; the output pin of the timer chip is used to output the internal trigger signal.

[0017] Furthermore, the internal and external trigger switching circuit is implemented using a relay, which serves as a switch for the internal and external trigger signals, and selects to receive the internal trigger signal generated by the internal trigger signal generating circuit or the external trigger signal from the external input; the internal and external trigger switching circuit supports the input of the external trigger signal of 0Hz-1kHz, and when the external trigger signal is selected to work, the power supply of the internal trigger signal generating circuit is turned off at the same time.

[0018] Furthermore, the Marx circuit includes a triggering part, a cascade charging and discharging part, and a load part;

[0019] The trigger part includes capacitor C01, capacitor C02, capacitor C03, capacitor C04, resistor R01, resistor R02, resistor R03, inductor L1, avalanche diode Q03 and transformer T; resistor R02, resistor R03 and capacitor C03 form a differential circuit, one end of resistor R02 and resistor R03 is grounded, and the other end is connected to the two ends of capacitor C03 respectively; the connection between capacitor C03 and resistor R02 serves as the input end of the trigger signal; the base of avalanche diode Q03 is connected to capacitor C03, the collector is connected to the primary side of transformer T through capacitor C02, and the emitter is grounded; the collector of avalanche diode Q03 is connected to a +12V power supply through resistor R01 and inductor L1 in cascade connection; capacitor C01 and capacitor C04 are connected in parallel, one end is grounded, and the other end is connected to the connection between resistor R01 and inductor L1;

[0020] The cascade charge and discharge part includes N units cascaded in sequence, where N is a positive integer; for the nth unit, 1≤n≤N, it includes an avalanche transistor Qn, a charge and discharge capacitor Cn, a current limiting resistor Rn, and a current limiting resistor R2n; the base of the avalanche transistor Qn serves as the input end of the nth unit, the collector is connected to a 250V power supply via the resistor Rn, and the emitter is grounded via the resistor R2n; the collector of the avalanche transistor Qn is connected to one end of the charge and discharge capacitor Cn, and the other end of the charge and discharge capacitor Cn serves as the output end of the nth unit; the input end of the first unit and the emitter of the avalanche transistor Q1 are respectively connected to the secondary side of the transformer T; for units with n≥2, the input end of the nth unit is connected to the output end of the n-1th unit, the base and emitter of the nth unit are connected, and the output end of the Nth unit serves as the output end of the cascade charge and discharge part;

[0021] The load part includes a resistor RL and an SMA connector. One end of the resistor RL is connected to the output end of the cascade charge and discharge part, and the other end is grounded. The SMA connector is connected in parallel with the resistor RL as the output end of the N-level Marx circuit.

[0022] Furthermore, the pulse voltage amplitude adjustment module is implemented by a 0dB-30dB attenuator with a step attenuation value of 1dB, which can achieve an adjustable output of a pulse amplitude of 27V-890V.

[0023] The beneficial effects of the present invention are:

[0024] The picosecond pulse source device with adjustable amplitude and fast rising edge described in the present invention integrates the external instrument that generates the trigger signal and the DC high-voltage power supply into the same circuit, realizes the characteristics of high amplitude and fast rising edge of the pulse source by debugging the Marx circuit, and realizes the amplitude and repetition rate adjustment of the pulse signal generated by the Marx circuit; finally, it can output an amplitude-adjusted fast rising edge positive polarity pulse signal, wherein the amplitude adjustable range is 27V-890V, the repetition rate adjustable range is 50Hz-1kHz, the rising edge pulse width is less than 145ps, and the positive pulse width is less than 420ps. The present invention integrates all modules into a cavity with a size of 330mm*240mm*75mm in length, width and height, and uses a knob to control the amplitude and repetition rate adjustment. In addition, the pulse source of the present invention has the advantages of simple operation and small size, which is conducive to modularization, and the amplitude and repetition rate are adjustable, which can meet the amplitude and repetition rate conditions in different application scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a circuit principle block diagram of the pulse source device of the present invention;

[0026] Figure 2 This is a circuit principle block diagram of the power conversion circuit in the pulse source device of the present invention;

[0027] Figure 3 This is a circuit diagram for generating an internal trigger signal in the pulse source device of the present invention;

[0028] Figure 4 This is a Marx circuit diagram of the N-level pulse source device of the present invention;

[0029] Figure 5 This is a physical diagram of the pulse source device of the present invention;

[0030] Figure 6 This is a diagram of the front panel of the pulse source device of the present invention;

[0031] Figure 7 This is a diagram of the rear panel of the pulse source device of the present invention;

[0032] Figure 8 This is a pulse waveform diagram generated by the pulse source device described in the present invention. DETAILED DESCRIPTION

[0033] The present invention will be further described below with reference to the accompanying drawings and examples.

[0034] This embodiment provides a picosecond pulse source device with adjustable amplitude and fast rising edge, such as Figure 1 As shown, it includes a power conversion circuit, an internal trigger signal generating circuit, an internal and external trigger signal switching circuit, an N-level Marx circuit and a pulse voltage amplitude adjustment module;

[0035] The power conversion circuit converts AC power into DC power for circuit use;

[0036] The internal trigger signal generating circuit is used to generate the internal trigger signal for triggering the Marx circuit. The internal trigger signal can achieve repetition frequency adjustment within a certain range.

[0037] Internal and external trigger signal switching circuit can realize the selection of internal or external trigger signal to trigger Marx circuit separately;

[0038] After receiving the trigger signal, the Marx circuit is used to generate a fast rising edge picosecond pulse signal;

[0039] The pulse voltage amplitude adjustment module adjusts the pulse voltage amplitude of the fast rising edge picosecond pulse signal and then outputs it.

[0040] The power conversion circuit principle is as follows Figure 2As shown, first, the first power supply circuit 1 converts AC 220V into DC 24V and 12V, the second power supply circuit 2 converts DC 24V into DC 250V, and the third power supply circuit 3 converts DC 24V into DC 5V, and finally DC 250V, 12V, and 5V power supplies are obtained for use by the pulse source circuit, of which 250V and 12V are used by the Marx circuit, and 5V is used by the internal trigger signal generating circuit and the internal and external trigger switching circuit.

[0041] In this embodiment, the internal trigger signal generating circuit uses a timer chip to generate a TTL square wave signal, and controls the voltage division of the peripheral voltage divider circuit of the timer chip through an external knob resistor to generate a 50Hz-1kHz TTL square wave signal.

[0042] The internal trigger signal generation circuit is a monostable trigger circuit built around a 555 timer (U5). A 5V DC power supply is supplied via decoupling capacitor C20 and connected to the power pin (pin 8) and reset pin (pin 4) of the timer chip. The timer chip's ground pin (pin 1) is connected to ground. Resistor R21, diode D2, adjustable resistor R23, and capacitor C21 are connected in series, with resistor R21 connected to the 5V DC power supply and capacitor C21 grounded. The cathode of diode D1 is connected to one end of resistor R22, while the anode of diode D1 is connected to the cathode of diode D2. The other end of resistor R22 is connected to the anode of diode D2 and the discharge pin (pin 7) of the timer chip, respectively. D1 and D2 control the charge and discharge direction, respectively. The trigger pin (pin 2) and threshold pin (pin 6) of the timer chip are interconnected and then connected between adjustable resistor R23 and capacitor C21. The control power pin (pin 5) of the timer chip is connected to ground via capacitor C22 to stabilize the reference voltage. The output pin (pin 3) of the timer chip is used to output the internal trigger signal. When C21 generates a voltage change due to an external signal and the voltage of the trigger pin (pin 2) is lower than 1 / 3 of the power supply voltage, the timer chip is triggered to output a high-level pulse with a fixed width.

[0043] The principle of the internal trigger signal generating circuit is as follows Figure 3 As shown in the figure, U5 is a timer chip that generates an internal trigger signal and outputs it through pin OUT. D1 and D2 ensure that the duty cycle of the square wave trigger signal does not change when the repetition rate is adjusted. R23 is a 0Ω-1kΩ adjustable resistor. By adjusting the resistance of R23, the repetition rate of the internal trigger signal can be controlled, achieving a TTL square wave internal trigger signal with an output frequency of 50Hz-1kHz.

[0044] In this embodiment, the internal / external trigger switching circuit is implemented using a relay, acting as a switch for the internal / external trigger signals, selecting between receiving an internal trigger signal generated by the internal trigger signal generating circuit or an external trigger signal input. The internal / external trigger switching circuit supports input of external trigger signals in the 0Hz-1kHz range. When the external trigger signal is selected, the internal trigger signal generating circuit is simultaneously powered off.

[0045] The internal and external trigger signal switching circuit can realize the internal trigger signal or the external trigger signal to trigger the Marx circuit separately, and a relay scheme is selected to control the selection of the internal and external trigger signals, and the power supply of the internal trigger generation circuit is turned off when the relay selects the external trigger.

[0046] The pulse source described in this embodiment uses a Marx circuit scheme to generate high-voltage pulses. The Marx circuit includes a trigger section, a cascaded charge-discharge section, and a load section. The cascaded charge-discharge section includes N sequentially connected units, each of which includes an avalanche transistor, a current-limiting resistor, and a charge-discharge capacitor. A DC power source is applied to the collector of the avalanche transistor through the current-limiting resistor and charges the charge capacitor when the avalanche transistor is in the off state. The emitter of the avalanche transistor is grounded through the current-limiting resistor. The base of the avalanche transistor in each unit is connected to the charge-discharge capacitor between the previous unit.

[0047] N-level Marx circuit Figure 4 As shown, the trigger part includes capacitor C01, capacitor C02, capacitor C03, capacitor C04, resistor R01, resistor R02, resistor R03, inductor L1, avalanche diode Q03 and transformer T; resistor R02, resistor R03 and capacitor C03 form a differential circuit, one end of resistor R02 and resistor R03 is grounded, and the other end is connected to the two ends of capacitor C03 respectively; the connection between capacitor C03 and resistor R02 serves as the input end of the trigger signal; the base of avalanche diode Q03 is connected to capacitor C03, the collector is connected to the primary side of transformer T through capacitor C02, and the emitter is grounded; the collector of avalanche diode Q03 is connected to the +12V power supply through resistor R01 and inductor L1 in cascade connection; capacitor C01 and capacitor C04 are connected in parallel, one end is grounded, and the other end is connected to the connection between resistor R01 and inductor L1.

[0048] The cascade charge and discharge part includes N units cascaded in sequence, where N is a positive integer; for the nth unit, 1≤n≤N, it includes an avalanche transistor Qn, a charge and discharge capacitor Cn, a current limiting resistor Rn, and a current limiting resistor R2n; the base of the avalanche transistor Qn serves as the input end of the nth unit, the collector is connected to a 250V power supply via the resistor Rn, and the emitter is grounded via the resistor R2n; the collector of the avalanche transistor Qn is connected to one end of the charge and discharge capacitor Cn, and the other end of the charge and discharge capacitor Cn serves as the output end of the nth unit; the input end of the first unit and the emitter of the avalanche transistor Q1 are respectively connected to the secondary side of the transformer T; the input end of the nth (n≥2)th unit is connected to the output end of the n-1th unit, the base and emitter of the nth (n≥2)th unit are connected, and the output end of the Nth unit serves as the output end of the cascade charge and discharge part.

[0049] The load part includes a resistor RL and an SMA connector. One end of the resistor RL is connected to the output end of the cascade charge and discharge part, and the other end is grounded. The SMA connector is connected in parallel with the resistor RL as the output end of the N-level Marx circuit.

[0050] Specifically, such as Figure 4 As shown, the secondary side of the transformer is connected to the first-stage Marx circuit, which consists of an avalanche transistor Q1, a current-limiting resistor R1, a capacitor C1, and a current-limiting resistor R2. The avalanche transistor Q1 is connected to a 250V DC power supply through the current-limiting resistor R1. The emitter of the avalanche transistor Q1 is grounded through the current-limiting resistor R2. The secondary side of the transformer is connected to the base of the avalanche transistor Q1. The capacitor C1 is connected to the collector of the first-stage Marx circuit and the base of the second-stage Marx circuit. The charging circuit of the first-stage Marx circuit consists of a 250V DC power supply, a current-limiting resistor R1, a capacitor C1, and a current-limiting resistor R4.

[0051] Each stage has the same Marx circuit structure, connected via capacitors. The collector of avalanche transistor QN is connected to capacitor CN, leading to the pulse source output. A load resistor RL is connected to the output to produce a negative pulse signal. The ground of the SMA connector is connected to CN and RL, while the positive terminal of the SMA connector is connected to the ground of the pulse source circuit. Ultimately, the pulse source outputs a positive pulse signal.

[0052] An amplitude adjustment module (attenuator) with a step attenuation value of 1dB is selected to adjust the amplitude of the pulse signal generated by the above-mentioned Marx circuit and output the pulse signal. The pulse voltage amplitude adjustment module described in this embodiment uses an amplitude adjustment module with 31 levels of 0dB-30dB steps of 1dB, which can achieve an adjustable output pulse amplitude of 27V-890V.

[0053] The pulse source of this embodiment integrates all circuit modules into one Figure 5In the cavity shown, the length, width and height of the cavity are 330mm*240mm*75mm. The front panel of the cavity is as shown in FIG. Figure 6 As shown, there are "amplitude adjustment" knob, "pulse output" connector, "external trigger input" connector, "internal trigger repetition rate" knob and "internal and external trigger switch" button. Figure 7 As shown, the AC 220V power input connector and the main power switch button are distributed.

[0054] When the pulse source of this embodiment uses internal trigger testing, the internal trigger repetition frequency is set to 1kHz, and the test waveform of the output pulse is as follows: Figure 8 The test results are shown in Table 1. The pulse output signal was tested with the amplitude adjustment knob ranging from 0dB to 30dB. As shown in Table 1, the pulse amplitude can be adjusted from 27.85V to 890.04V. Within this amplitude range, the maximum rising edge duration is 145.79ps and the minimum is 137.78ps. The maximum pulse width is 420.86ps and the minimum is 410.75ps.

[0055] Table 1 Pulse output under internal trigger mechanism

[0056]

[0057]

[0058] In external trigger mode, the pulse source circuit described in this embodiment sets the external trigger signal repetition rate to 1kHz, 500Hz, 200Hz, 100Hz, and 50Hz, respectively, and adjusts the amplitude adjustment knob to 5dB. The output pulse waveform is then tested. The test results in Table 2 show that at different repetition rates, the pulse amplitude ranges from 495.18V to 501.77V, the rising edge duration ranges from 145.49ps to 146.03ps, and the positive pulse width ranges from 419.37ps to 420.45ps.

[0059] Table 2 Pulse output under external trigger mechanism

[0060] Serial number External trigger repetition rate Pulse amplitude (V) Rising edge (ps) Positive pulse width (ps) 1 1kHz 495.18 145.75 420.08 2 500Hz 499.03 145.91 420.38 3 200Hz 500.10 146.03 420.45 4 100Hz 501.77 145.98 419.76 5 50Hz 501.26 145.49 419.37

[0061] In summary, the present invention provides a picosecond pulse source device with adjustable amplitude and fast rising edge. In order to obtain a pulse source with high amplitude, fast rising edge and adjustable amplitude and repetition rate, this embodiment improves the traditional positive pulse signal Marx circuit, adopts a negative pulse Marx circuit and reverses the output signal to obtain a positive pulse output signal, and increases the number of Marx circuits to obtain a positive pulse signal with higher amplitude and faster rising edge. In order to achieve adjustable pulse signal amplitude and repetition rate, an internal trigger signal generation and adjustment circuit is designed to adjust the repetition rate of the pulse signal, and an amplitude adjustment module is used to adjust the amplitude of the pulse signal. After testing, a positive polarity pulse signal with an adjustable amplitude of 27V-890V, an adjustable repetition rate of 50Hz-1kHz, a rising edge of less than 145ps, and a positive pulse width of less than 420ps can be obtained. Under different repetition rates, the amplitude output of the pulse signal is basically the same, and the rising edge and positive pulse width are basically the same. The pulse source of the present invention can meet the amplitude and repetition rate requirements in different application scenarios.

[0062] The above description is only a specific embodiment of the present invention and is not intended to limit the present invention. Any equivalent structure or equivalent transformation made using the contents of the present invention description and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A picosecond pulse source device with adjustable amplitude and fast rise time, characterized in that: It includes a power conversion circuit, an internal trigger signal generating circuit, an internal and external trigger signal switching circuit, a Marx circuit and a pulse voltage amplitude adjustment module; The power conversion circuit is used to convert AC power into DC power for use by circuits and modules within the device; The internal trigger signal generating circuit is used to generate the internal trigger signal for triggering the Marx circuit. The internal trigger signal can realize repetition frequency adjustment. The internal and external trigger signal switching circuit is used to realize the selection of the internal trigger signal or the external trigger signal, and trigger the Marx circuit based on the selected trigger signal; After receiving the trigger signal, the Marx circuit is used to generate a fast rising edge picosecond pulse signal; The pulse voltage amplitude adjustment module adjusts the pulse voltage amplitude of the fast rising edge picosecond pulse signal and then outputs it.

2. The picosecond pulse source device with adjustable amplitude and fast rise time according to claim 1, characterized in that: The power conversion circuit converts 220V AC power into DC 250V, 12V and 5V power. The 250V and 12V power are used by the Marx circuit, and the 5V power is used by the internal trigger signal generation circuit and the internal and external trigger switching circuit.

3. The picosecond pulse source device with adjustable amplitude and fast rise time according to claim 1, characterized in that: The internal trigger signal generating circuit is implemented based on a timer chip and can generate a TTL square wave signal with a frequency of 50Hz-1kHz.

4. The picosecond pulse source device with adjustable amplitude and fast rise time according to claim 1, characterized in that: In the internal trigger signal generating circuit, a 5V power supply is supplied through a decoupling capacitor C20 and is connected to the power pin and reset pin of the timer chip, and the ground pin of the timer chip is grounded; a resistor R21, a diode D2, a variable resistor R23, and a capacitor C21 are connected in series in sequence, the resistor R21 is connected to the 5V power supply, and the capacitor C21 is grounded; the cathode of the diode D1 is connected to one end of the resistor R22, the anode of the diode D1 is connected to the cathode of the diode D2, and the other end of the resistor R22 is connected to the anode of the diode D2 and the discharge pin of the timer chip respectively; the trigger pin and the threshold pin of the timer chip are interconnected and then connected between the variable resistor R23 and the capacitor C21; the control power pin of the timer chip is grounded through the capacitor C22 to stabilize the reference voltage; the output pin of the timer chip is used to output the internal trigger signal.

5. The picosecond pulse source device with adjustable amplitude and fast rise time according to claim 1, characterized in that: The internal and external trigger switching circuit is implemented by a relay, which serves as a switch for the internal and external trigger signals, and selects to receive the internal trigger signal generated by the internal trigger signal generating circuit or the external trigger signal input from the outside; The internal and external trigger switching circuit supports the input of external trigger signals of 0Hz-1kHz. When the external trigger signal is selected, the power supply of the internal trigger signal generating circuit is turned off at the same time.

6. The picosecond pulse source device with adjustable amplitude and fast rise time according to claim 1, characterized in that: The Marx circuit includes a trigger part, a cascade charge and discharge part, and a load part; The trigger part includes capacitor C01, capacitor C02, capacitor C03, capacitor C04, resistor R01, resistor R02, resistor R03, inductor L1, avalanche diode Q03 and transformer T; resistor R02, resistor R03 and capacitor C03 form a differential circuit, one end of resistor R02 and resistor R03 is grounded, and the other end is connected to the two ends of capacitor C03 respectively; the connection between capacitor C03 and resistor R02 serves as the input end of the trigger signal; the base of avalanche diode Q03 is connected to capacitor C03, the collector is connected to the primary side of transformer T through capacitor C02, and the emitter is grounded; the collector of avalanche diode Q03 is connected to a +12V power supply through resistor R01 and inductor L1 in cascade connection; capacitor C01 and capacitor C04 are connected in parallel, one end is grounded, and the other end is connected to the connection between resistor R01 and inductor L1; The cascade charge and discharge part includes N units cascaded in sequence, where N is a positive integer; for the nth unit, 1≤n≤N, it includes an avalanche transistor Qn, a charge and discharge capacitor Cn, a current limiting resistor Rn, and a current limiting resistor R2n; the base of the avalanche transistor Qn serves as the input end of the nth unit, the collector is connected to a 250V power supply via the resistor Rn, and the emitter is grounded via the resistor R2n; the collector of the avalanche transistor Qn is connected to one end of the charge and discharge capacitor Cn, and the other end of the charge and discharge capacitor Cn serves as the output end of the nth unit; the input end of the first unit and the emitter of the avalanche transistor Q1 are respectively connected to the secondary side of the transformer T; for units with n≥2, the input end of the nth unit is connected to the output end of the n-1th unit, the base and emitter of the nth unit are connected, and the output end of the Nth unit serves as the output end of the cascade charge and discharge part; The load part includes a resistor RL and an SMA connector. One end of the resistor RL is connected to the output end of the cascade charge and discharge part, and the other end is grounded. The SMA connector is connected in parallel with the resistor RL as the output end of the N-level Marx circuit.

7. The picosecond pulse source device with adjustable amplitude and fast rise time according to claim 1, characterized in that: The pulse voltage amplitude adjustment module is implemented by a 0dB-30dB attenuator with a step attenuation value of 1dB, which can achieve an adjustable output of a pulse amplitude of 27V-890V.

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