Application Cases

Experiment Name: Research on High-Speed Modulated Pulsed X-ray Source Technology and Its Application in Martian X-ray Communication

Research Direction: Communication Technology

Objective:
Mars is a focal area for deep-space exploration. As Mars exploration advances, future Mars probes will face challenging conditions that traditional communication methods may struggle to handle, such as the blackout zone during atmospheric entry and Martian dust storm environments. Therefore, exploring novel information carriers and investigating new communication technologies is essential. X-ray communication (XCOM) is an emerging space communication technology. Leveraging the high-penetration characteristics of X-rays, XCOM systems are expected to function effectively in complex deep-space environments.

This study provides a crucial theoretical foundation for implementing Martian X-ray communication and developing high-speed modulated pulsed X-ray sources. It is also anticipated to offer communication technology support for China's future Mars exploration missions.

Testing Equipment:
ATA-4315 high-voltage power amplifier, signal amplifier, signal generator, oscilloscope, DC power supply, GMXS prototype tube, etc.

Experimental Procedure:

Figure 1: GMXS Prototype Tube

The GMXS was custom-manufactured, and after sealing and high-voltage resistance testing, a GMXS prototype tube with X-ray modulation capability was obtained. As shown in Figure 1, the gate electrode and tungsten filament are housed inside the cathode shield, while the anode metal target is positioned inside the anode shield, which has an X-ray emission window on one side. At the cathode end, the filament and gate electrode are connected to wires and routed out from one end of the tube for convenient voltage application. At the anode end, the anode metal target is connected to a metal terminal for applying high voltage.

Figure 2: Schematic Diagram of GMXS Pulse Response Test Equipment Connections

The pulse response characteristics of the GMXS were indirectly measured by detecting the anode pulse current. Based on this method, an equivalent experimental platform was constructed, with the equipment connections shown in Figure 2. A DC power supply was used to power the cathode filament of the GMXS prototype tube for thermionic emission, with the voltage set to 6.5 V and the filament current at 0.88 A. A 2 kΩ resistor was connected to the anode, and a 200 V high-voltage power supply was used to power the anode. This 200 V anode voltage generates an electric field to accelerate electrons and collect electrons within the gated tube. The anode voltage changes were monitored using an oscilloscope. The pulse shape of the anode voltage effectively reflects the X-ray pulse characteristics generated by the GMXS. The anode voltage change divided by the resistance value (2 kΩ) indirectly yields the electron current striking the anode metal target. Since the anode voltage is low, it is insufficient to generate X-rays from the anode metal target, thus avoiding radiation protection issues associated with pulsed X-ray emission. Additionally, due to the low anode voltage, the free electrons in the cathode slot experience insufficient electric field force, requiring a higher control voltage applied to the gate electrode to ensure normal electron pulse emission. The initial gate signal was generated by a signal generator, producing a square wave signal with a repetition frequency of 10 kHz to 1 MHz and an amplitude of 2 V. This signal could not directly drive the gate electrode, so a signal amplifier was used to amplify the initial signal. In the experiment, the ATA-4315 power amplifier was used to amplify the low-voltage square wave signal from the signal generator, and the amplified high-voltage signal was applied to the gate electrode. Following the connections in Figure 2, all equipment was grounded. The physical setup of the experimental equipment is shown in Figure 3.

Figure 3: GMXS Pulse Response Test Platform

Experimental Results:
The results for gate frequencies of 10 kHz, 100 kHz, and 1 MHz are shown in Figures 4–6, respectively. At a fixed gate repetition frequency, adjusting the signal amplifier gain produced gate voltage pulses of varying intensities. Figures 4–6 show results for gate voltage peaks of 40 V, 60 V, 80 V, and 100 V. The green waveform represents the pulse voltage waveform output by the signal amplifier (positive), while the blue waveform represents the voltage change detected at the anode (negative, generated by electron pulses striking the anode).

Figure 4: Comparison of Anode Voltage Waveform and Gate Signal at 10 kHz Gate Frequency

The results for a gate frequency of 10 kHz are shown in Figure 4. Under different gate voltage peaks, the anode voltage changes responded well to the gate signal, with no significant pulse width broadening or phase delay. This indicates that the GMXS exhibits excellent pulse response performance at a gate frequency of 10 kHz.

Figure 5: Comparison of Anode Voltage Waveform and Gate Signal at 100 kHz Gate Frequency

The results for a gate frequency of 100 kHz are shown in Figure 5. The pulse response performance of the GMXS remained excellent. Under a tenfold increase in repetition frequency, the rising and falling edges of the gate signal output by the signal amplifier slowed slightly, with some noticeable high-frequency components. However, the anode voltage pulses did not further narrow the plateau region, and the modulation source did not respond to some high-frequency components.

Figure 6: Comparison of Anode Voltage Waveform and Gate Signal at 1 MHz Gate Frequency

The results for a gate frequency of 1 MHz are shown in Figure 6. Due to the limitations of the power amplifier performance, the gate voltage pulses exhibited noticeable distortion. However, the anode voltage waveform still showed a good response. This indicates that the GMXS maintains excellent pulse response performance at a gate frequency of 1 MHz, meaning the X-ray modulation source can achieve a modulation rate of 1 MHz.

Aigtek ATA-4315 High-Voltage Power Amplifier:

Figure: Specifications of the ATA-4315 High-Voltage Power Amplifier