DocumentCode :
2204345
Title :
First experimental measurement of the free streaming plasma mode
Author :
Hoffman, J.R. ; Muggli, P. ; Katsouleas, T. ; Joshi, C.
Author_Institution :
Dept. of Electr. Eng.-Electrophys., Univ. of Southern California, Los Angeles, CA, USA
fYear :
2000
fDate :
4-7 June 2000
Firstpage :
148
Abstract :
Summary form only given, as follows. The "free streaming" mode is magneto-static (w=0) plasma eigenmode sustained by steady currents flowing in the plasma in alternate directions. For this reason it has also been referred to as the "picket fence" mode. The existence of this mode has been theorized for more than 30 years, but has never been observed experimentally. This mode is excited in the DARC source where a static electric field alternating with a spatial wavenumber. k/sub 0/ is transmitted into a plasma through a relativistic ionization front. We present the first experimental measurement of the "free streaming" mode. This was accomplished by placing an array of microstrip coils, (whose impedance is matched to a 50 ohm load from zero to 1 GHz), inside of the proof of principle DC to AC radiation convertor (DARC source). With this arrangement the phasing of the interaction region and the microstrip coil array is held constant, thus allowing measuring each coil in the array independently, instead of simultaneously. The wavenumber of the free streaming mode, variations of the magnetic field amplitude with the incident electric field strength and the plasma density were measured, and are consistent with theoretical predictions. The implications of the existence of the free streaming mode is the validation of the assumption that the electrons born via laser ionization are essentially at rest, or at most, born with an isotropic velocity distribution.
Keywords :
plasma density; plasma instability; relativistic plasmas; DARC source; DC to AC radiation convertor; free streaming mode; free streaming plasma mode; incident electric field strength; isotropic velocity distribution; laser ionization; magnetic field amplitude; magneto-static plasma eigenmode; microstrip coil array; microstrip coils; picket fence mode; plasma density; relativistic ionization front; spatial wavenumber; static electric field; steady currents; Coils; Converters; Impedance; Ionization; Magnetic field measurement; Microstrip antenna arrays; Phased arrays; Plasma measurements; Plasma sources; Plasma waves;
fLanguage :
English
Publisher :
ieee
Conference_Titel :
Plasma Science, 2000. ICOPS 2000. IEEE Conference Record - Abstracts. The 27th IEEE International Conference on
Conference_Location :
New Orleans, LA, USA
ISSN :
0730-9244
Print_ISBN :
0-7803-5982-8
Type :
conf
DOI :
10.1109/PLASMA.2000.854825
Filename :
854825
Link To Document :
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