From the Armationem entry.
With the body turned into a particle mass, the caster can spread a positively charged particle swarm (a group of his own positive particles) away from the main body, and thus able to prepare an electric field of a certain span. The caster can control the swarm – Negi manages this using wind magic – and thus the field itself, arbitrarily switching it from dunamis/potentia to energeia and vice versa. When the field is actualised, the caster’s negatively charged main body (particle mass) will be powerfully drawn towards the positively charged particle swarm, due to the electrical potential difference between them. Essentially, the caster uses an electrostatic discharge as a medium to achieve extremely high agility.
(Note that 150km/s is the average speed of a stepped leader during a lightning strike and the main ‘branch’ occurring within the opened circuit will be many times faster. In any case, the exact speed of discharges depends on local conditions, but it should exceed 2,260km/s.)
During this, the caster’s main body (a high-speed negatively charged particle mass) collides with the molecules and atoms in the air. As the massive amount of kinetic energy becomes ionisation energy and causes repeated impact ionisation (an electron avalanche), this releases a large amount of charged particles, resulting in a burst of electricity (hence, “lightning”).
The negatively charged particles that compose the caster’s main body will for the most part join with the positively charged particles newly generated within the circuit. Thus, the caster cannot simply repeat the high-speed movement to another positive particle swarm. This magic is not as simple as “moving as fast as lightning”.
Benjamin Franklin proved that lightning is electricity in 1752. However, before the modern era, lightning was assumed to be “the fire of the sky”. For example, Aristotle believed that lightning was caused by the burning of ejected exhalations (9b) and Hesiod referred to Zeus’ thunderbolts as “sacred flame” (iere phloz [ιερη φλοξ]). In magical terms, ‘to become a charged particle mass’ is equivalent to ‘becoming fire’.
To put it this way, you can say that ‘Raiten Taisou’ is a spell to change the caster’s body into fire, and mutating yourself into a jinni (eg. the Spirit of the Lamp in the story of Aladdin); jinn, beings made of fire, will never ‘burn out’, similar to how living beings can ‘grow back’ from injuries. Thus, during impact ionisation, even though the caster has lost his initial charged mass, he can absorb the charged particles within the circuit as a replenishment, and maintain his body (and life).
By unleashing the lightning within the caster (Khilipl Astrape) onto an actualised electric field, the caster can create a sudden, extreme electrical potential difference, resulting in a large electrical strike: Perfectus Plasmationis Per Emissionem, “Chihayaburu Ikazuchi”.
‘Chihayaburu’ is ancient Japanese, meaning “mighty, great, vigourous power”. ‘Chihayaburu’ in this case is written as “breaking a thousand rocks” (千磐破). Thus, “Thousand Rocks Breaking Lightning”.
In the case of ‘Raiten Taisou’, until the caster removes the positively charged particles from his main body and to elsewhere in his expanded electric field, he cannot use a circuit for high-speed movement. However, with ‘Duplex Complexio’ and a doubled ‘Mega Dunamene’ (‘Raiten Sousou’), the caster can change particle arrangement during movement, allowing him to create the next circuit while still in mid-movement. As the caster can create new circuits indefinitely, the caster can remain in a high-speed form infinitely – Constant Lightning Form.