THE EFFECT OF THERMAL SPREAD ON THE TWO-STREAM RF GAIN FROM A NEUTRAL PLASMA BEAM
Abstract
When ions and elecrons are aceleraed in the same direction to different velociies, RF signals will be amplified along this traveling plasm. SINCE THE THERAL VELOCITY SPREAD OF THE PARTICLES WILL MAE THE IPARTED VELOCITY DIFFERENCE LESS PRONOUNCED, ONE MAY EXPECT TO OBSERVE LESS GAIN THAN IS PREDICTED BY THE SIMPLE THEORY FOR COL STREAMS. CALCULTIONS ARE PRESENTED HERE WHICH SHOW THI REDUCTION. Typicaly, the optmum gain goes down to two-thirds of the cold value when the random electron velocity is a little as 10% of the relative drift velocity. The plasma equations are linearized and it is assumed that a) the plasma is electricaly nearly neutral, (b) hydrogen ions are used, (c) the thermal ion velocity is small compared with the ion drift velociy, (d) the frequencies considered are relatively small, and (E) the electron drift velocity is only slightly larger than the ion drift velocity. Up to certain degrees of thermal spread the gain passes through a maximum as one varies the frequency. When the thermal spread increases, the frequency at which this optimum occurs decreases. The gain disappears completely when the above-mentioned thermal velocities become very large compared with the relative drift velocity. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 21, 1961
- Accession Number
- AD0261896
Entities
People
- B. Hoeks
Organizations
- Stanford University