Just the facts:

From:
http://www.quackwatch.org/01QuackeryRelatedTopics/kirlian.html

Kirlian Photography
Stephen Barrett, M.D.
Kirlian photography allegedly depicts the body's "aura," a so-called "human energy field" that is said to be not ordinarily visible. During the procedure, the object, such as a person's hand, is placed on a photographic emulsion within an apparatus that generates a high-voltage (15,000 to 100,000 volts), low-amperage, high-frequency electric current. The resulting photo shows a fuzzy glow surrounding the outline of the object. Proponents correlate these patterns with acupuncture meridians and claim that "auric" qualities reveal changes in health and emotional state. Kirlian photography has also been claimed useful for demonstrating changes before and after chiropractic spinal manipulation. However, scientific investigators have shown that Kirlian effects depend on physical factors that are well understood.

Kirlian photography is named after Semyon Davidovich Kirlian (1900-1980), a Russian electrician who observed that an electric spark can "take its own picture" as it passes through a photographic emulsion. This phenomenon had been well known to physicists and electrical engineers since the earliest days of photography. But in 1939, Kirlian proclaimed that he was photographing a supernatural human energy field.

The Kirlian photographic process requires a high-voltage, high-frequency, alternating current supply. The basic process -- a corona discharge phenomenon -- occurs when an electrically grounded object discharges sparks between itself and an electrode generating the electrical field [1]. Two set-ups can be used to take Kirlian photographs. In the first, one end of the circuit is attached to an electrode above a piece of film, the other to an identical electrode below the piece of film. The second method involves grounding one electrode of the power supply and placing a dielectric slab on the other. A piece of film is then placed on the slab. Any object placed between two films in the first method, or on the film in the second method, will produce a beautiful photograph as "streamers" of charged particles leave any "bumpy" features of the object and pass through the film [2].

Kirlian himself did not understand the involved science. To him, the "fuzzy" field surrounding any object was a photograph of its "aura." He was ignored by Russian scientists, but during the early 1960s the Russian press and popular magazines promoted him as a "great discoverer." American and European journalists and pseudoscientists flocked to see him and returned home ready to "study the aura" and "probe the bioenergy field."

Kirlian photography is alleged to detect all types of disease (even before physical signs appear) and emotional states. Many "energy healers," "clairvoyants," and other occult practitioners still rely on it today. "Supernaturally gifted" people are claimed to generate unusually dramatic photos. However, scientific investigation has found that the outcome depends on the type of film, the voltage, the skin resistance (which can be affected by perspiration and the amount of pressure of the finger on the film), how well the subject is electrically grounded, the humidity of the room, the exposure time, the photographic development time, and even the order of the photograph in a series [3,4]. Moreover, coins and water droplets can generate Kirlian "auras" as effectively as living things. In fact, at least 22 physical, chemical, and photochemical characteristics can influence the coronal discharges seen in Kirlian photos.

References
Guiley RE. Harper's Encyclopedia of Mystical & Paranormal Experience. San Francisco: Harper, 1991, pp 313-315.
Coker G. Kirlian photography and the "aura." ASTOP fact sheet, 1983.
Watkins AJ, Bickel WS. A study of the Kirlian effect. The Skeptical Inquirer 10:244-257, 1986.
Watkins AJ, Bickel WS. The Kirlian technique: Controlling the wild cards. The Skeptical Inquirer 13:172-184, 1989.

INTRODUCTION
First of all, let's make one thing clear: although I've called this page Kirlian Photography Page the technical name is Electrophotography. In fact there's no Kirlian Photography at all, what we may see in an electrophotography is the Kirlian Effect : the modification of the electric discharge around the object due to biological alterations of the electrical parameters of the specimen.

Also the luminous halo around the object has nothing to do with the AURA, it's just a particular type of electrical discharge... so: no AURA please!!!

DISCHARGE ORIGIN
What is this bright luminous halo produced around the objects? Well, the discharge we were talking about it's called corona discharge and happens to appear when there's a high surface charge density in specific points over the object. From this points the accumulated charges (either excess or lack of them) interact with the surrounding atmosphere.

Why the underlining? Because, what produces the bright halo, are the atmosphere's molecules interacting with the accelerated charges in those "specific" points we've mentioned before. In fact the gas is being ionized, therefore the color (light's wavelength) produced is related to the type of gas present in the surrounding atmosphere...

Bluish halos? Well, the main component of the air we breath is Nitrogen, it tends to emit bluish light...

And what if we replace nitrogen for neon? Yes... you know the answer, reddish halos then... (sorry esoteric folks... the color of the emitted light is related to the gaseous atmosphere. Also, the colors registered on the film, depend on even additional parameters...

Now comes the main question: If emitted light (luminous halo) appears due to highly charged areas, how do we increase this surface charge density?

The answer is quite simple:

Increase the electric field (means: use High Voltage).
Introduce a dielectric (means: increase charge)
Keep pumping charges after the introduction of the dielectric (means: use a generator).

Why all this? Perhaps you don't know, but the introduction of a dielectric while keeping the electrical field constant produces a charge current and increases the surface charge density by a value equal to the dielectric constant of the medium introduced...

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