Laser with non-electron plasma

[AlexanderSinn]

• Small enough (< few 100s of lines), otherwise it should probably be split into smaller PRs
• Tested (describe the tests in the PR description)
• Runs on GPU (basic: the code compiles and run well with the new module)
• Contains an automated test (checksum and/or comparison with theory)
• Documented: all elements (classes and their members, functions, namespaces, etc.) are documented
• Constified (All that can be const is const)
• Code is clean (no unwanted comments, )
• Style and code conventions are respected at the bottom of https://github.com/Hi-PACE/hipace
• Proper label and GitHub project, if applicable

[MaxThevenet]

Thanks! A single test would be nice, e.g., compare no ions vs. light ions (e.g. mass 10x the electron mass), to observe an effect.

[huixingjian]

I have examined the pull request in the linear regime by means of the analytical theory. And the results work fine.
First I reverse the value of the mass of ion and electrons in the input script as

ions.density(x,y,z) = ne
ions.mass = m_e
ions.charge=q_e
ions.ppc=1 1
electrons.charge = -q_e
electrons.mass = m_p
electrons.density(x,y,z) = ne
electrons.ppc = 1 1
diagnostic.diag_type = yz

And it generates an opposite plasma wave as expected.

And I changed the value of the mass of ion and electrons to 1000*m_p and 2*m_e respectively as

ions.density(x,y,z) = ne
ions.mass = 1000*m_p
ions.charge=q_e
ions.ppc=1 1

electrons.charge = -q_e
electrons.mass = 2*m_e
electrons.density(x,y,z) = ne
electrons.ppc = 1 1

And result matches perfectly with the analytical result