There were some laws and instances of enforcement of those laws, related to abuse or killing of another person’s slave. Georgia codified these in their slave codes. I am not aware of any laws specifically against the rape of a slave. There were many laws, including some requiring castration, for various offenses (including sex offenses) allegedly committed by slaves.

The closest thing I can find to a law prohibiting rape of slaves by owners or whites is in Colonia Louisiana’s Code Noir, which restricted interracial relations resulting in mulatto children.

As to the criminal charge itself, if it had existed, the name of the charge would have likely varied from state to state, as do the titles of laws and offenses in the modern day.

There are many recorded instances of slaves having been raped. It was not uncommon, and was ingrained in the culture. Elizabeth Keckley, a former slave who later worked in the Lincoln White House, wrote of sexual assault in her memoirs.

While the sources I consulted to double-check lack of a law relating to the rape of another slave owner’s slave didn’t affirm the negative that I could find, these are some works I consulted:

Alabama Slave Codes (1833)

[Missouri’s Early Slave LawsMissouri Slavery Laws

Everett, Donald E., “Free Persons of Color in Colonial Louisiana,” The Journal of the Louisiana Historical Association, Vol. 7, No. 1.

Bardaglio, Peter. “Rape and the Law in the Old South: ‘Calculated to excite Indignation in every heart,’” The Journal of Southern History, Vol. 60, No. 4