All life on Earth, including plants and animals alike, is protected from the harmful UV radiation of the Sun by a protective layer of ozone in Earth’s atmosphere.
A study published by British Antarctic scientists in Nature Magazine in 1985 highlighted a repeating springtime hole in the Antarctic ozone layer. Scientists warned that humanity could wipe out the ozone layer by 2050, without which UV-induced skin cancer rates would increase, and the ecosystem as we know it would disintegrate, resulting in large-scale death and destruction of biodiversity.
Today, however, our ozone layer is recovering and rebuilding itself, all thanks to an unprecedented action that followed this discovery. Scientists worldwide began intensive field studies in the Antarctic region, taking measurements from the ground and the atmosphere using platforms such as balloons and high-altitude aircraft. As a result, they identified that the leading cause of this ozone depletion was the chlorine present from a class of manufactured compounds called chlorofluorocarbons (CFCs). CFCs were found in numerous widely available products such as aerosol sprays in cosmetic products, paints and food industry, air conditioners and fridges etc.
The information about the harmful effects of ozone depletion spread among the public, and political leaders worldwide were motivated to take action to correct the trajectory of CFC gas emissions. In 1987, the Montreal protocol acknowledged that the worldwide emissions of certain substances could significantly deplete and modify the ozone layer, which is likely to result in adverse effects on human health and the environment. The control measures it listed included a directive for developing alternate chemicals that could replace CFCs and provided subsidies to the developing nations to help them switch away from CFCs. In the years following, as scientists continued atmospheric studies, more restrictive amendments were added to the Montreal Protocol to ensure ozone recovery. In an unprecedented move, every country has agreed and signed the protocol, making it the only existing universal treaty to be ratified. The Montreal Protocol is therefore often regarded as the most successful international environmental agreement. In a sense, this treaty is a symbol of unity on a global scale.
Today, scientists continue to study chlorine and ozone levels in Earth’s atmosphere, along with numerous other important targets related to climate change, weather, air quality, wildfires, etc. The data generated by these scientists are shared publicly and with governments to help make decisions and policies that impact not only the current population but also the upcoming generations.
One such experiment focused on Earth’s atmosphere is currently underway at Harvard University. The Harvard Halogens team works on monitoring systems flown aboard a NASA ER-2 aircraft, that measure levels of inorganic chlorine and bromine in the stratosphere. The instrument uses heaters to thermally dissociate larger molecules containing these elements. Their job is to instantly heat incoming air, moving at ~20 m/sec. Harvard originally used silicon strip heaters, but the brittle strips would often break under the wide ~300°C operating temperature span, and harsh environment. The failures resulted in loss of data and high replacement cost. Moreover, it caused undue delays in the project timelines. Datec’s solution to this problem was a direct replacement Stainless-steel thick film heater element.
One of the key challenges was the dimension of the heater. Each strip was 0.25mm thick, 60mm long, and 8mm wide. Datec designed a thick film heater to be deposited on either side of the stainless steel strip to generate enough heat to increase the temperature of the strip from 25 °C to 250 °C in 3 seconds.
Figure 1 Datec Stainless Steel Strip Heater
Figure 2 Assembled Strip Heaters
After rigorous testing at Datec, heaters were shipped to Harvard for additional performance tests. Here is the initial feedback from the customer:
“They are so far meeting and exceeding expectations, and we are very encouraged by the results! We were able to power up strips individually and easily bring them up to the expected working 250°C temperature and beyond! The strips handled it with no apparent problems. They really looked good! We truly appreciate the huge effort that must have gone into manufacturing and testing all these strips in record time.”
Datec’s team strives to solve our customer’s thermal challenges and push the limits of technology for the betterment of the world.