## 1 Introduction  
Sealed neutron tubes are widely used in neutron logging, neutron radiography, the cargo security system of ports, airports, and stations due to the advantages of safety, miniaturization, portability, good tightness [1; 2; 3], etc. For the sake of improving the nuclear reaction efficiency and reducing the size of neutron tubes, several methods were adopted, for example, the secondary electrons suppression [4], the deuterium or tritium absorption capabilities enhancement [5], and vacuum stability promotion [6]. The suppression of secondary electrons will benefit the reduction of the power and current on the target and the alleviation of the power load, thus improving the heat dissipation capability of the target and the stability of neutron tubes [7]. Several methods have been utilized in neutron tubes for the purpose of secondary electron suppression, including the Faraday cup, magnetic field mitigation, applying biased voltage between the accelerator electrode and the target, introduction of resistance, and the combination of the Faraday cup with the biased voltage method [8]. The main disadvantage of these methods is that they occupy the space of the neutron tube. In addition, some of these methods, such as the Faraday cup method, actually exhibit inadequate secondary electron suppression effects. The laser processing method proposed by [PERSON] et al. [9] is a novel way for the secondary electron suppression, having the benefits of not needing to introduce additional components, low cost, etc. In this work, laser processed oxygen-free high-conductivity copper (OFHC) is proposed to mitigate the secondary electron emission. Ti film coating is traditionally used in the sealed neutron tubes to absorb hydrogen and its isotopic molecules [10]. Ti film can store hydrogen isotopes steadily with high capacity at room temperature via the formation of metal hydrides, e.g., titanium and hydrogen isotopes, to adsorb more deuterium or tritium on the target. Consequently, Ti film coating can provide sufficient reaction materials for nuclear reactions [11]. To further improve the nuclear reaction efficiency and working stability of neutron tubes, it is necessary to develop a novel film coating for the neutron target. [PERSON] et al. put forward that Ti-Zr-V-Hf film coatings have the lowest activation temperature (\(\sim\)140 \({}^{\circ}\)C) and higher pumping speed and capacity for H\({}_{2}\) than previous binary and ternary alloys film coating getters [12; 13; 14]. From the perspective of maintaining the vacuum stability in a long-running process, Ti film as a kind of essential getter is usually applied in the neutron tubes. However, there is no report on the application of novel quaternary Ti-Zr-V-Hf non-evaporable getter film coatings in sealed neutron tubes. On the other hand, the thermal conductivity of the Ti-Zr-V-Hf film coated substrate is a key factor which can affect the overall heat transfer performance of the target and the operating life of neutron tubes. Thus, the thermal conductivities of Ti-Zr-V-Hf film will be investigated and compared to the Ti film with laser-treated and untreated OFHC substrates in this work. The working temperature of the neutron target is usually over 150 \({}^{\circ}\)C [15; 16] so the deuterium gas absorbed in the film can desorb on the film surface of the target. This kind of desorption can reduce the energy loss of D\({}^{+}\) and consequently improve the nuclear reaction and neutron yield. To improve the neutron beam quality, enhance the operating life, and reduce the volume of neutron tubes further, the combination of the laser processing method and the single metal and quaternary alloy film coatings is proposed in this paper for the first time. Quaternary Ti-Zr-V-Hf coating with a lower activated temperature of \(\sim\)150 \({}^{\circ}\)C is proposed to be applied in neutron tubes to improve the hydrogen/deuterium/tritium pumping property.