## 2 Materials and Methods  
### Micro-Emitter Modification  
An impaction-style micro-emitter used in both greenhouse irrigation systems (model: Modular 7000, Jain Irrigation Inc., Fresno, CA, USA) and in previous SSCDS proof of concept experiments [22] was selected for modification (Figure 1a). Such micro-emitters consist of a static impaction plate which atomizes the columnar spray jet in a radial pattern with a large cone angle (150\({}^{\circ}\)) and wetted diameter (2100 mm), and marginal vertical throw (320 mm) (Figure 1b). The factory impaction plate has a toothed design (Figure 1a) that tends to coarsen the spray and direct it into non-uniform radial \"rays\" of spray. This creates a wide statistical span in the droplet spectra and irregular deposition. While this is desirable for irrigation to mitigate evaporation, finer droplets with a narrower span are desired for canopy applications.  
Through preliminary lab trials, it was hypothesized that increasing the static impactor plate concavity could reduce the cone angle of the spray, subsequently reducing the wetted diameter. Moreover, on vertically inverted placement of micro-emitter as depicted in Figure 1b, pertinent customization could increase the vertical throw of micro-emitters. Such modifications were critical to restrict the spray swath within the canopy, i.e., reduce off-target spray movement and increase in canopy deposition. Eliminating the teeth in the factory impaction plate and using a smooth-edged design also reduced the droplet spectrum, potentially improving in-canopy coverage. Thus, the static impactor plate of selected irrigation micro-emitter was modified with smooth edges and concavity ranging from 20-60\({}^{\circ}\) in an increment of 5\({}^{\circ}\). The modified impactor plate was fixed to the micro-emitter assembly and evaluated in the lab. A randomly selected modified and non-modified micro-emitter was operated at 310 kPa, and a portable projector curtain was stationed in the background for imaging. A measuring scale was attached to the background for  
Figure 1: An off-the-shelf (**a**) micro-emitter with (**b**) a larger cone angle and wetted diameter, and a marginal vertical throw customized to (**c**) modified irrigation micro-emitter with (**d**) impactor plate concavity of 50\({}^{\circ}\) to acquire (**e**) a smaller cone angle and wetted diameter, and a higher vertical throw (not drawn to scale; all linear dimensions are in mm).  
dimension referencing. The Red-Green-Blue images of the spray flux were captured using a visible-infrared sensor (model: Duo Pro R, FLIR Systems, Inc., Wilsonville, OR, USA) from a distance of 2 m and was analyzed in ImageJ (open source) software to evaluate the cone angle, vertical throw, and wetted diameter. The trial results indicated that a static spreader with 50\({}^{\circ}\) concavity (Figure 1d) was optimal to achieve the desired spray pattern with enhanced vertical throw and reduced wetted diameter (Figure 1c,e). Thus, the micro-emitter with modified static spreader (hereafter termed as'modified irrigation micro-emitter') was selected for field evaluation in a SSCDS configuration. Additionally, the droplets of the micro-emitters/nozzles were characterized using a droplet size analyzer (model: VisiSize 15, Oxford Lasers Ltd., Didcot, Oxon, UK). The spray flux was passed through the optical sensing zone of the analyzer. The analyzer was set to analyze 1000 droplets, and the volume mean diameter (Dv0.5) corresponding to the micro-emitter/nozzle were evaluated. The droplet spectrum was classified based on the Dv0.5 values as per ASABE S572.3 standard [29].