How to use the Global Source Shutter in DEVICE

The global source shutter in DEVICE can be used to investigate the transient response of a component to a light pulse (CHARGE) or a heat pulse (HEAT). In the CHARGE solver, the shutter can be used to turn on/off optical generation objects and in the HEAT solver, the shutter can be used to turn on/off heat sources to simulate the response of the device.

Definitions of the different options can be found in these KB pages (CHARGE, HEAT) and is also provided below,

• SHUTTER MODE: disabled for no shutter, step on and step off for step functions, pulse on and pulse off for a pulse with on and off times. The time shutter function will be plotted as the option is chosen for ease of use. The on and off times can then be specified.
• SHUTTER TON: Sets the ON time of the shutter.
• SHUTTER TOFF: Sets the OFF time of the shutter.
• SHUTTER TSLEW: Sets a slew in the stepping of the shutter. This feature is useful in helping the solver to converge where a sharp step in the optical shutter tend to makes the solver diverge.
• SHUTTER SLEW FUNCTION: linear for a linear transition between off and on states, log for an exponential change between the off and on states. The log option uses the “shutter slew cutoff” value.
• SHUTTER SLEW CUTOFF: If the “log” option is selected for the shutter slew function, the shutter uses the logarithmic function to step from this value to 1 (for turning on) and from 1 to this value (for turning off). The switch from 0 to the cutoff value (and back) is abrupt and happens in a single time step.

• ILLUMINATION POWER SCALING: This option can be used to scale the amplitude of the source. By default the value is set to ‘1’ which means no scaling.

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A post was split to a new topic: Can I model modulated optical source using the global shutter in DEVICE?

I have a question somewhat related to this. Can the shutter be toggled repeatedly?

Hi @chuan.xie, unfortunately this cannot be done currently. The best you can do is a full pulse (turn on and then turn off).

Hi @aalam,

Thanks for the reply, but this is a bit unfortunate. This seems a useful feature. for example, when I driver the heater with a alternating source, I would like to know the temperature variations at a given point. Hope it can be added.

To drill down my question a bit further. When I add a thermal boundary condition with the solver boundaries at fixed temperature, I am able to assign the temperature of one boundary to different values at different times. and the simulations runs successfully. When I add a thermal boundary condition by choosing the heater (a solid) as a “boundary” with fixed power, I am also able to assign different heating power for different times, DEVICE allows me to do that with no complaint. However, when I try to run the simulation in this case, I get an error message (after meshing, I think). I wonder how these two scenarios are different from the solver’s prospective.

Regards,

Chuan

By the way, when the source is turned on, the transient response is calculated. Turning it off, however, simply stops the simulation. At least this is how it works for me. The program does not allow me to set a stop time, so the cooling part of the transient can be calculated as well. Is this how it should be?

Regards,

Chuan

I agree. We do have plans to let users define their own shutter signals in the long term which will allow you to do this. Unfortunately for now the shutter only has these limited options. My apologies for the inconveniences.

There is no limitation in using a transient power boundary condition. I am guessing the problem is coming form the fact that when you switch the boundary condition to transient simulation power, you no longer have any boundary condition defined in the system that can provide a reference temperature to the simulation region (this can be done with a temperature, convection, or even radiation boundary condition). For a HEAT simulation to work you must have a reference temperature defined somewhere because without it there is unique solution to the temperature of the system. If you only have a power boundary condition then this condition is no longer satisfied. Adding one of the above mentioned boundary conditions somewhere in your simulation setup should fix the problem.

The end time for the simulation is usually defined by the definition of the boundary conditions. The last time that you define for the transient boundary conditions define the simulation end time. That and the time you set in the definition of the global shutter (whichever is the largest). If you want to run the simulation to a time after the pulse ends then make that the last time step you set in the transient boundary condition definition.