Comparison with other electrostatic generators Other electrostatic machines such as the Wimshurst machine or Bonetti machine work similarly to the Van De Graaff generator; charge is transported by moving plates, disks, or cylinders to a high voltage electrode. For these generators, however, corona discharge from exposed metal parts at high potentials and poorer insulation result in smaller voltages. In an electrostatic generator, the rate of charge transported (current) to the high-voltage electrode is very small. After the machine is started, the voltage on the terminal electrode increases until the leakage current from the electrode equals the rate of charge transport. Therefore, leakage from the terminal determines the maximum voltage attainable. In the Van de Graaff generator, the belt allows the transport of charge into the interior of a large hollow spherical electrode. This is the ideal shape to minimize leakage and corona discharge, so the Van de Graaff generator can produce the greatest voltage. This is why the Van de Graaff design has been used for all electrostatic particle accelerators. In general, the larger the diameter and the smoother the sphere is, the higher the voltage that can be achieved.
ComPaRIsOn wITh otHeR eLeCtRoSTatIc geneRAtors OTheR eLectrosTaTic macHiNes sUCh AS the wIMshurst macHine oR bonETTi mAcHINe work simiLarly to the van de grAaff genErator; chaRgE is traNspOrted bY MoVIng plaTes, Disks, Or cYLIndeRs tO A High VoltaGe ElectroDe. for thEsE gEneraTorS, hoWEver, corOna diScharge FrOm expOsED meTal PaRTs at hIGh POtentIals anD poorEr inSulaTioN rEsult In smallER voltAGeS. in An ElEcTrostatiC generaTor, tHe raTE oF charge transPORtED (curreNt) to the hiGh-voLtaGe elecTroDe iS very smaLL. afteR the mAChinE iS starTED, tHe Voltage on THe termInal elEctrode increaseS uNTIl The leakaGE cUrrent froM ThE elecTroDe eQuAlS THe rate oF chaRGe traNsPort. therEForE, LeaKagE FrOm the tERmiNaL determINeS the maxImUM vOLtaGe aTtAinablE. In the vAn De grAaFf generator, the belt allOws the traNspOrT oF charge iNto THe InteRIor oF a Large holLow spHerIcAl ELecTrOde. THIs iS ThE idEal shape To MINiMIZe leakAGe anD CorONa DiSChArge, sO THE Van De graafF GEnerator cAn pRoduce thE gReatEst voltagE. tHIs is why the van de Graaff DesigN hAS BeEn useD FoR all eleCTrostAtiC pARticle AcceleRators. IN GenEraL, THe larGer tHE diAmetEr and thE smoOtHer the spherE Is, thE higHer the Voltage tHat can BE AcHieVed.