Power Beam

Samus Aran's Power Beam (パワービーム), known as the Normal Beam (ノーマルビーム) in the 2D games, is her basic weapon made of Chozo technology, and it comes with her Power Suit. The Power Beam does little damage to more powerful enemies, although it can easily kill weaker enemies. The scans from the Metroid Prime Trilogy states that the beam is good at clearing the room of weaker enemies. The Power Beam, despite being a recently-made weapon, packs considerably less power than ancient Chozo weapons, as seen when Samus first used it on Mother Brain's Zebetites shields, revealing they were immune to it, but when Grey Voice attacked with a century-old weapon, it was able to penetrate the shields. Over the course of the Metroid games, Samus has received various upgrades to her beam:

Also, depending on the suit she wears, the upgrades she possesses and the situation she is in, she can sometimes absorb things in her environment using her suit and transfer the power to her beam. This ability is demonstrated in Super Metroid, when she gains the powerful Hyper Beam to defeat Mother Brain (though the weapon was first acquired by the Baby and then transferred to her Arm Cannon), in Metroid Prime when she acquires the Phazon Beam to defeat the Metroid Prime, and in Metroid Prime 2: Echoes, when she draws in with the Charge Beam shards of pure Phazon shot at her by Dark Samus and fired them back at her dark nemesis.
 * Long Beam
 * Spazer Beam
 * Wide Beam
 * Wave Beam
 * Ice Beam
 * Plasma Beam
 * Charge Beam
 * Dark Beam
 * Light Beam
 * Annihilator Beam
 * Nova Beam
 * Diffusion Beam

In Metroid Prime Hunters, Samus's beam has a rapid-fire effect. It fires three shots at once, then a fourth, before beginning to charge.

On a side note, in Metroid Prime Hunters: First Hunt the Power Beam used an ammunition system. This is the only game where it has done so. If the player ran out of ammo they would no longer be able to fire the Power Beam fully automatically, and would be unable to use Missiles. This may have been a product of the training hologram, however.

Official Metroid Prime website
Weapon effect: Highly effective offensive tool

Weapon range: 3-10 m

Weapon potential: High

"The Power Beam is the basic energy unit produced by Samus Aran's standard Arm Cannon. The Power Beam is expelled from Samus' Arm Cannon. Close observation indicates that this is the Bounty Hunter's most frequently used offensive tool. The Power Beam may be charged, dramatically increasing the weapon's effectiveness. Ineffective against advanced shields and engineered enemies."

Metroid Prime manual
"This is Samus's standard beam, which you can fire continuously by rapidly tapping the A Button. As with all beam weapons, the Power Beam becomes much stronger once Samus finds the Charge Beam power-up. Once Samus has found the Charge Beam, press and hold the A Button to charge up her shot, then release the A Button to fire a powerful blast."

Metroid Prime 2: Echoes manual
"Fire the Power Beam continuously by rapidly tapping the A Button. It becomes much stronger when Samus uses the Charge Beam. Hold the A Button to charge (which also engages a tractor beam effect that draws power-ups toward Samus), then release it. The Power Beam can open blue hatches and has infinite ammo."

Metroid Fusion manual
"This is the standard beam Samus possesses at the beginning of the game."

Metroid: Zero Mission manual
"This is Samus' standard beam weapon."

Metroid: Other M On-Screen Tutorial
ATTACK

Press 1 to fire your beam.

Metroid: Other M manual
"Press 1 to fire a beam. Press and hold 1 and release to fire a powerful Charge Beam."

Metroid: Other M Samus Screen data
"Controls: Fire with 1. Press and hold 1 until fully charged and release to shoot a Charge Beam ."

Normal Beam/Charge Beam
Samus' standard hand cannon can wipe out the more common creatures infesting the Bottleship, while an added charge function ups the damage quotient significantly.

Metroid Prime Hunters
In Metroid Prime Hunters, the Power Beam has infinite ammo but is weak offensively; however makes up with rapid fire (especially in Story Mode). A normal shot does around 6 damage. The Power Beam is a popular weapon with many MPH players, especially in small arenas without the Imperialist. As with many other weapons, the Power Beam does more damage with a headshot.

Trivia
*		In the Metroid Prime Trilogy, the beams affected the Arm Cannon in their own unique way when charging. In the case of the Power Beam, beams of light would appear from the sides of the Arm Cannon. In the New Play Control! and Metroid Prime Trilogy versions of Metroid Prime, this effect is absent. However, this graphical effect is retained in the re-releases of Metroid Prime 2: Echoes and Metroid Prime 3: Corruption.

**				Another, less noticeable, effect that is not present in Trilogy version of Metroid Prime is the heat waves which emanate from the Arm Cannon after rapid-firing the Power Beam.

*		The Power Beam was supposed to appear in Marvel: Ultimate Alliance as well as several other weapons of Samus' and Samus herself, however, she ultimately did not appear in the final game because Nintendo did not give the developers permission to include her. This iteration of the Power Beam appears to be based on that of Prime.

*		In Metroid Prime, the symbol for the Power Beam is a hand print presumably combining its index finger with its middle finger, and putting it together with the ring finder, with the pinky and thumb sticking out. This is the hand configuration Samus must have to activate the Power Beam.

*		In Metroid: Zero Mission, an uncharged shot from the Power Beam does 1 damage.





*		The Power Beam is also called "Energy Beam."

*		In Metroid Prime, the Power Beam was modeled and skinned by Gene Kohler.

*		Chozo Ghosts are immune to all natural forms of energy, yet are vulnerable to the Power Beam. The Power Beam is therefore an unnatural form of energy.

*		In Metroid Prime 3: Corruption, the Power Beam is presented as being more powerful during cutscenes than it is during gameplay. Samus is seen killing Pirate Troopers in a single shot, while in game play it takes 20 shots or two full charged shots.