Wikipedia
The pentagrammaton or Yahshuah is a constructed form of the Hebrew name of Jesus originally found in the works of Athanasius Kirchner, Johann Baptist Grossschedel (1619) and other late Renaissance esoteric sources. It is to be distinguished from the name Yahshua found in the works of the Sacred Name movement in the 1960s, though there has been some conflation or confusion between the two. The pentagrammaton Yahshuah has no support in archeological findings, such as the Dead Sea scrolls or inscriptions, nor in rabbinical texts as a form of Joshua. Scholarship generally considers the original form of Jesus to be Yeshua, a Hebrew Bible form of Joshua.
The essential idea of the pentagrammaton is of an alphabetic consonantal framework Y-H-Sh-W-H, which can be supplied with vowels in various ways. (Also, the "W" can be converted into a "U", since the Hebrew letter ו waw writes either a [w] consonant sound — later on pronounced [v] — or a long [u] vowel sound: see Mater Lectionis.)