Collective Ion Acceleration in the Vacuum Systm with Insuilated Anode

Abstract

Summarysr periments are described of ion acceleration in diode with insulated anode mounted on two E-beam generators that deliver 2kJ and 1 kJ of energy in 1 MeV;50 ns and 0.55 MeV,80 ns pulses accoraingly. The maximum yield of protons 1014+3.1013 with energy in (1.9+ 2.7) MeV range were measured with accompanying electron'beam current 18 kA and electron energy 0.8 MeV on 2 kJ maching.The suppression of charging prepulse by inserting a dielectric piece in cathode terminal on it resulted in increased ion energy up to 5 MeV and total yield of protons with energy in the (2.7 + 5) MeV region up to 101t331012.By application of several (from 1 to 3) post anode electrodes on 1 kJ machine the.energy of ions were increased up to 4.2 MeV,which corresponds to (E./E )max =14.Reproducibility and effectiveness of acceleration processes were investigated. Introduction. Besides well known methods of the ion acceleration in relativistic electron beams drifting in neutral gases new approaches of ion acceleration are 4n progress now at several laboratories2'3.The simplicity of applied technique and rapid successes in attaining high ion yields and energies stimulate further investigations in these directions. Experimental. Wed havecarried some experiments on collective ion acceleration on the device similar to one proposed in 293 using two E-beam machines that delivers 2 kJ and I kJ of energy in I MeV,50 ns and 0.35 MeV,80 ns pulses.Our generators differed from those used in mentioned above works by long pulse rise time (20 ns) and absence of prepulse switch,suppressing the microsecond duration pulse during the charging phase, To investigate the influence of these factors on effectiveness of acceleration processes a lot of experiments were fulfilled on modified accelerator guns,in which suppression of prepulst, and some shortening of current rise time were attained by insertion insulators-caprolon pieces (L=5+9cim) between the needle tungsten cathode and shank. In first experimental run the electron beam from 2 mm in diameter tungsten needle was injected through the central hole in the insulated anode (fabricated from polyethylen, caprolon ,teflon and plexyglass) in the vacuum chamber 300 mm in diameter and 300 mm in length and impinged on the target grounde. through the resistor of the Faraday cup (F.c.) or directly. The plasma,generated on the anode surface due to the bombardment of electrons and surface breakIsttitute of Nuclear Physias P .O.Box 25 Tomsk-50, USSR. 4248 0018-9499/79/0600-4,Fig. I The scheme of experimental setup with electrodes assembly mounted on I kJ machine. down was the source of ions. In another series of experiments on I kJ E-beam generator additional floating and grounded (alternatively) electrons in'post-&anode region were established (see fig. 1 ). The measurements of ion-electron beam was made by F.c. (R= 50 mQ ) on which litium or multilayered copper foils ( 20 mkm ) were ajusted. The total gun current and voltage were measured by shunt,( R= 0.11S ) and capacity voltage divider. The total number of prot...

Формирование Кольцевых Структур Пучка При Коллективном Ускорении Ионов В Системе С Диэлектрическим Анодом

“…Длина ускорения", как правило, не пре-вышала 10 cm [2], наблюдалось снижение энергии ионов E p при увеличении длины эквипотенциальной области дрейфа электронного пучка [4]. В вакуумной камере с лайнерами-линзами [5] …”