How could vary the Helium emission spectrum?

[Ignition]

In a condition of high pressure, how could vary the Helium emission spectrum?
Is this spectrum modified from the pressure?

 

[johanw]

In very high pressures, the electrons will feel the electrons of other helium atoms so it will have an influence on the spectrum. I don't know exactly how such a spectrum will look, but for helium I think you needc really high pressures to give a measurable effect. I think the effect is more significant on elements with vacant positions in the outer shells since these are usually much further away from the nucleus so they are more sensitive to outside influences.

 

[Redbelly98]

There is both a broadening and a shift in atomic spectral lines as the pressure increases.

For example: for the 1083 nm line in helium, the broadening has been calculated to be 12 MHz/Torr and the shift -1.9 MHz/Torr at 300 K.

See table II on page 7 here:
http://cfa-www.harvard.edu/~hrs/PubList/PRAHe2004.pdf