High-intensity ultraviolet germicidal lamp (below)

During the epidemic, how to cut off the spread of the virus in public places is the top priority. In the first half, we introduced the advantages of ultraviolet light disinfection and the shortcomings of ultraviolet disinfection light sources on the market in epidemic prevention. In the second half, we will share some achievements in the research and development of radio frequency focused plasma excitation technology. If you want to know the content of the first half, please click → High-intensity ultraviolet sterilization lamp (above).

04 Breakthrough and Prospect of Radio Frequency Focused Plasma Excitation Technology

In order to solve the shortcomings of the current rare gas ionization extreme ultraviolet light source and meet the growing research needs of scientific and technological workers and testing and measurement units, the team members overcame difficulties and developed a new type of high-efficiency radio frequency focused plasma excitation technology after more than two years of hard work [11]. The multi-gas high-brightness extreme ultraviolet light source developed using our radio frequency focused plasma technology solves the long-standing problems of single energy and low light flux of laboratory extreme ultraviolet light sources, and its performance greatly exceeds that of existing international products.

This technology uses a specially designed RF field focuser, which breaks through the limitation of the wavelength characteristic size of the traditional waveguide resonant cavity, forms a millimeter-level local RF field, and greatly enhances the electric field strength of the local field. The 433MHz extreme ultraviolet light source product that has been successfully developed can achieve an extreme ultraviolet light power output per unit length of 40 times that of traditional methods, and the overall brightness is more than 10 times higher than that of foreign commercial products. It has achieved very good use and demonstration effects in the frontier laboratories of more than 20 universities and research institutes at home and abroad, and gradually replaced the existing commercial products that have been monopolized by foreign countries for a long time. This provides a solid technical accumulation for the development of UVC band RF focusing ultraviolet lamps.

05Research work carried out and expected results
Faced with the menacing epidemic, starting from January 30, the team members took quick action and actively explored solutions for high-intensity ultraviolet sterilization light sources to contribute their own strength to the fight against the epidemic. Drawing on the luminescence principle of radio frequency focused plasma excited extreme ultraviolet light sources, the team members replaced the rare working gas with a small amount of amalgam pills (5mg), and successfully achieved the emission of the 253.7nm dominant (more than 85%) spectral line.

Expected indicators:
● Light intensity: 1 meter away from the lamp head, greater than 4000um/cm2;

● Time: 24V lithium battery, 7-8 hours after full charge;

● Area: 5m2-10m2 per time coverage;

● Irradiation time: stay for 30s-60s to completely kill the virus;

The advantages of ultraviolet germicidal lamps based on RF focused plasma excitation technology are:

1> The RF field energy is focused to the millimeter level, generating a high electric field strength of up to 109V/m, the power density is increased by more than 100 times, and the plasma density is 1-2 orders of magnitude higher than that of traditional discharge tubes.

2> In plasma excited by high-frequency microwaves, energy is mainly transferred to the electronic part of the atom, and the ultraviolet light conversion efficiency is increased by more than 10 times, with high brightness.

3> It is easy to realize high-power lamp tubes, and the flux is 20 to 100 times that of current ultraviolet lamps. It can be used for rapid sterilization and disinfection, and the sterilization rate and application space volume are greatly improved.

4> Integrated with advanced high-power solid-state RF source as the driver, 24V DC voltage drive, no electrodes and high voltage required, safer and more reliable;

5> The volume of the bulb can be reduced to 10mm at the shortest (up to 500mm at the longest), the solid-state RF source is small in size, can be driven by lithium batteries, portable, and easier to integrate into mobile devices such as robots.

6> The light bulb has no electrodes and its life span is more than 10,000 hours.

7> The use of amalgam is greatly reduced, reducing environmental pollution.

In the future, based on the RF focused plasma excitation technology, the R&D team will give full play to its own advantageous resources, go all out, overcome difficulties, and quickly carry out the design, optimization and production of high-intensity, large-area, high-efficiency solid-state RF ultraviolet sterilization light source products, so as to develop high-intensity ultraviolet lamp products for large-area rapid sterilization and disinfection in open spaces such as hospitals, schools, and high-speed rail stations, and complete daily air purification work such as sterilization and disinfection in combination with the intelligent robot inspection platform. Effectively cut off the transmission route of the new coronavirus among the population, save energy and time for overloaded doctors and high-speed rail staff, reduce the risk of cross-infection between doctors and patients, and help prevent and control the epidemic.

References

[1] National Health Commission Statistics and Information Center Epidemic Prevention and Control Update, http://www.nhc.gov.cn.
[2] National Health Commission "Guidelines for Public Protection against Pneumonia Infected by Novel Coronavirus", People's Publishing House, 2020.
[3] Ultraviolet germicidal lamp "GB19258-2012", China National Committee for Standardization, 2012.
[4] Hirayama Hideki, Jo Masafumi, Maeda Noritoshi, Kashima Yukio, RecentProgress in AlGaN-Based Deep-UV LEDs, DOI:10.5772/intechopen.79936,2017.
[5]https://www.kickstarter.com/projects/740978067/cleanty-worlds-smallest-and-most-powerful-uvc-led
[6] Technical Specification for Disinfection in Medical Institutions (WS/T367-2012), National Health Commission, 2012.
[7] Hospital Air Purification Management Standards (WS/T368-2012), National Health Commission, 2012. [8] Duan S M, Zhao X S, Wen R F, et al. Stability of SARS coronavirus in human specimens and environment and its sensitivity to heating and UV irradiation[J]. Biomed Environ Sci, 2003,16(3):246-255. [9] Darnell M E, Taylor D R. Evaluation of inactivation methods for severe acute respiratory syndrome coronavirus in noncellular blood products[J]. Transfusion, 2006,46(10):1770-1777. style="font-size:12px;color:#666666;">[10]Spiros Kitsinelis, Spyridon Kitsinelis, Light Sources: Basics of Lighting Technologies and Applications, CRC press, ISBN 9781138034044 - CAT# K31585, 2017.