Beamed Power
First attempt to describe KSPI-E beamed power
The object of beamed power is to transfer power from vessels/rovers with high availability of power, to vessels/rovers with low availability.
There are serval key advantage of using beamed power.
- Mass savings. Reactor and their power generators are heavy.
- Cost savings. It saves funds as it becomes more economical than hauling your own power supply into orbit or down a planet or moon.
- Improved safety. You can keep you nuclear reactors safely on the ground and still benefit from their power.
- High performance. Thanks to its ability concentrate a lot of power, it has the potential for unreasonable levels of performance which would not be possible with onboard reactors.
- Improved utilisation. Extend the utilization of expansive reactors after the main purpose is completed
In KSPI-E we currently differentiate between 4 kind of modes op operation at beamed power part can perform.
Transmitting. Transmitting means the supply of beamed power into the beamed power network. You don’t set a transmitter to a particular target, or aim it in a particular direction, just activating the Transmit button is enough. A transmitter capable part must either be connected directly to a beam generator or has an onboard integrated beam generator before it is allowed to transmit beamed power. Beam generator can either transmit on a specific wavelength set in the VAB or switch in flight between an array of wavelengths. Parts that are capable of transmitting tend to be heavier due to the required targeting actuators and rigid structure. A not so obvious secondary usage of part capable of transmitting beamed power is the ability to be used for transmitting science data.
Receiving. Receiving means that the part will attempt to collect any power available in the beamed power network in a particular narrow or wide bandwidth range. In contrast to transmitting , the direction a receiver is facing, does matter! but some part are more flexible in this regard than others. The most flexible receivers are parts that are capable of pivoting in 2 axis. Parts that are capable of pivoting in one axes can receive anything covered by the axis and requires rotating of the vessel along it’s axes to receive in all direction and fixed dishes only receive optimally in one particular direction. Regarding receiving part in general we can make types are receiver, thermal receiver and electric receivers. Thermal receivers simply first allow the received beamed power to heat up a liquid which is then transported to either a thermal electric generator of thermal engine (which it is connected to) to release it energy. When used to convert to energy, the efficiency very much depends on the amount of radiators available. Not that if the amount of power becomes too much, and the system become over-saturated with heat, it might be wise to limit the percentage op power received in the part menu.
Link Up Link up is option available on beamed power receivers capable of directly passing a beamed power signal to another part on the vessel configured for relay. In contrast to receiving, the direction the part faces, does not matter.
Relay The relay button comes available on a transmitter if either another part on a vessel is linked up in a compatible bandwidth, or the part can simultaneously receive and transmit for multiple directions (like with phased array). Similarly to transmitting, the direction at which part is aimed at does not matter.
The overall efficiency of a beamed power transmission depends on many variables, first the electrical power needs to be converted to beam in a specific wavelength. This is called Wall to Beam efficiency. In general, the efficiency is higher for longer wavelength (like microwave), specialized transmitter parts and in campaign mode, on your unlocked tech nodes. After the beamed power is transmitted into the network, the effective beamed power depends on a combination of distance, transmitter aperture an receiver diameter and the receiver beamed power to electric power efficiency.
The combination Beam Wavelength and Transmitter aperture diameter determines how tight a wavelength will remain, the shorter the wavelength, and larger the diameter, the smaller the effective spotsize.
Spot size = 1.44 * distance-to-spot * wavelength / (aperture diameter)
As long as the spotsize is smaller than the receiver diameter, it will receive all beamed power. When the spotsize is larger than the effective diameter of the receiver, it cannot receive all beamed power, but because the beamed energy is mainly focused in the center, even if the receiver diameter it twice as small as the spotsize, it still receive half of the total beamed energy. (For example a receiver with a diameter of 5m will still receive 50% of beamed power when the spotsize is 10m in diameter).
The Mk1/Mk2 Thermal Receiver is the first beamed power receiver ( it has the advantage that it is compatible with any wavelength, a property of thermal receivers). It basically operates by absorbing the beamed energy and generate thermal heat. The thermal heat can then be used directly for propulsion or energy production when connected with a thermal electric generator. The Mk1/Mk2 Thermal Receiver optimal receival is 100% from the sides and 0% from the top or bottom. This blindspot can be a major problem when ascending because during a natural gravity turn, the bottom will point directly to KSC. Therefore placing a transmitter next to the KSC is the worst location for a transmitter when ascending. there are basically 2 methods of combatting this. Either place a beamed power transmitter a few kilometer to the west or use a transmitter on a ship east from KSC. Putting the transmitter westward is the easiest and has to advantage of allowing you to park a transmitter at a high hill or mountain, which benefits from low atmospheric absorption. The disadvantage is that it requires a retrograde orbit. On the other hand using a ship vessel as transmitter has the advantage is that you can place vessels in a prograde orbit, requiring less propellant. Regarding the launch, the normal gravity turn is not the ideal ascend as it would reduce the time you are in range of your transmitter. Instead use a vertical launch and turn horizontal at 35000 m. This will ensure the thermal receiver sides are exposed as long as possible to your transmitter. Next one in space, you are advice to use a thermal receiver dish, which functions as a slave, feeding the thermal receiver for power. The big advantage of a dish is that they can receive beamed power direct from the bottom of the vessel. You can do even better if you combine it with a power pivot from infernal robotics, aiming the dish at the surface transmitter.
