= Rotor Lamination =

Laminated launch loop rotors will have good magnetic properties and will rapidly disperse and oxidize in the atmosphere after a rotor-release catastrophe.  Worst case, thin flakes survive and cut.

[[ http://metglas.com/products/magnetic_materials/2605SA1.asp | Metglas 2605SA1 ]] looks good, higher temperature than 2605HB1M. [[ attachment:2605sa1.pdf | datasheet ]] downloaded 2017/02/11

||<-5:> '''Metglas 2605SA1'''                                                            ||
|| Curie temperature       ||  395C / 668K || || saturation induction    || 1.56 Tesla   ||
|| thickness               || 23 μm        || || density                 || 7.18 g/cm³   ||
|| Thermal Expansion       || 7.6 ppm/°C   || || Iron vaporization temp  || 3140 K       ||
|| Tensile Strength        || 1 GPa        || || Elastic Modulus         || 100 GPa      ||
|| Iron                    || 85 to 95%    || || [[ https://www.cdc.gov/niosh/npg/npgd0344.html | IDLH Fe₂O₃]] || 2.5g/m³ ||
|| Silicon                 || 5 to 10%     || || [[ https://www.cdc.gov/niosh/npg/npgd0552.html | IDLH SiO₂]]  || 3.0g/m³ ||
|| Boron                   || 1 to 5%      || || [[ https://www.cdc.gov/niosh/idlh/1303862.html | IDLH B₂O₃]]  || 2,0g/m³ ||
|| resistivity             || 1.3 μΩ-m     || ||<-2>                                     ||
||<-2> 60 Hz and 1.4 T                     || || Induction at 80 A/m     || ≥1.35 T      ||
|| Core Loss               || ≤0.17 W/kg   || ||Exciting Apparent Power* || 1.1 (VA/kg)  ||

|| [[attachment:2605SA1_coreloss.jpg | {{attachment:2605SA1_coreloss.jpg}}]] || Core loss appears proportional <<BR>>to (frequency × flux )^1.8^ .<<BR>><<BR>> Figure from datasheet. ||

Naively, assume that the rotor is excited at 100 KHz and produces 150 KN of thrust against a payload moving at a relative speed of 3 km/s with a wavelength of 0.1 m, an excitation frequency of 30 KHz.  Assume a similar synchronous frequency (it will actually be slightly lower).  Assume a sled length of 100 meters.

||<-2> End of acceleration and track conditions ||
|| payload speed                 || 11 km/s   ||
|| power                         || 1.65 GW   || extracted from rotor ||
|| track coil pitch              || 0.11 m    ||
|| track field frequency         || 100 KHz   ||
|| rotor speed                   || 14 km/s   ||
|| rotor mass density            ||  3 kg/m   ||
|| rotor relative speed          ||  3 km/s   ||
|| rotor ΔV                      || 13.1 m/s  || Slowdown under sled                            ||
|| rotor time under sled         || 33.3 ms   || 100m / 3000 m/s relative                       ||
|| rotor acceleration under sled || 393 m/s²  || delta V / time                                 ||
|| rotor force per meter         || 1179 N/m  || acceleration times mass density                ||
|| rotor total force             || 117.9 KN  || the rest goes into the (rebounding?) track     ||
|| rotor coil pitch              ||           || This varies along the track, longer at the end ||
|| rotor field frequency         || low       || in ''rotor'' frame of reference                ||

== Failure and oxidation ==

Iron has a specific heat of 25.1 J/(mol·K), vaporizes at 3140K, and has a heat of vaporization of 340 kJ/mol .  Naively, to go from 400K to vaporization requires 410 kJ/mol or 16 MJ/kg .  The rotor moves at 14 km/s, the kinetic energy is 98 MJ/kg, so there is more than enough energy to vaporize the rotor foil and ignite it.   '''Further study and experimentation needed'''; perhaps most of the energy will end up heating the surrounding air, and the foil will fragment and fall to the ocean surface and then the sea floor.

------
=== Tape Wound Toroidal Transformers ===

 * http://www.butlerwinding.com/tape-wound-toroidal-transformer/
 . 0.000125” = 3.175 μm
 . available in alloys of silicon steel, nickel-iron, cobalt-iron, and amorphous metals
 .