compressor c 1 connects with the hot end of the first stage regenerator rg 1 the cold end of the first stage regenerator rg 1 connects with the cold end of the first stage pulse tube pt 1 the hot end of the first stage pulse tube pt 1 connects with the first stage reservoir r 1 through the first stage inertance tube i 1 the first stage acoustic power amplifier a 1 is inside the first stage pulse tube pt 1 the distance between the first stage acoustic power amplifier a 1 and the hot end of the pulse tube is x the length of the first stage acoustic power amplifier a 1 is l x u2212 l gt 0 as shown in fig2 a pulse tube cryocooler with an acoustic power amplifier consists of a first stage compressor c 1 a first stage regenerator rg 1 a first stage pulse tube pt 1 a first stage acoustic power amplifier a 1 a first stage inertance tube i 1 a first stage reservoir r 1 a second stage compressor c 2 a precooling section of second stage regenerator rg 21 a section of second stage regenerator rg 22 a second stage pulse tube pt 2 a second stage acoustic power amplifier a 2 a second.